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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Jun. 29, 2018
Document And Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	HESM
Entity Registrant Name	Hess Midstream Partners LP
Entity Central Index Key	0001619739
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Public Float		$ 324.6
Common Units
Document And Entity Information [Line Items]
Entity Units Outstanding	27,297,031
Subordinated Units
Document And Entity Information [Line Items]
Entity Units Outstanding	27,279,654

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 20.3	$ 47.2
Accounts receivable—affiliate
From contracts with customers	62.2	58.5
Other receivables	0.8	1.3
Other current assets	2.8	4.4
Total current assets	86.1	111.4
Equity investments	67.3
Property, plant and equipment, net	2,664.1	2,520.5
Other noncurrent assets	2.2	3.2
Total assets	2,819.7	2,635.1
Liabilities
Accounts payable—trade	15.3	12.2
Accounts payable—affiliate	15.8	22.5
Accrued liabilities	64.5	32.7
Other current liabilities	6.8	7.0
Total current liabilities	102.4	74.4
Other noncurrent liabilities	6.4	5.4
Total liabilities	108.8	79.8
Partners' capital
General partner	14.9	14.8
Total Hess Midstream Partners LP partners' capital	516.8	520.8
Noncontrolling interest	2,194.1	2,034.5
Total partners' capital	2,710.9	2,555.3
Total liabilities and partners' capital	2,819.7	2,635.1
Common Unitholders - Public
Partners' capital
Common and subordinated unitholders	357.1	357.7
Common Unitholders - Affiliate
Partners' capital
Common and subordinated unitholders	39.5	40.5
Subordinated Unitholders - Affiliate
Partners' capital
Common and subordinated unitholders	$ 105.3	$ 107.8

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
shares in Millions, $ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Revenues and other income

Affiliate services

$ 661.7

$ 565.6

Type of Revenue [Extensible List]

hesm:AffiliateServicesMember

Other income

$ 0.7

$ 0.2

Total revenues and other income

662.4

565.8

Costs and expenses

Operating and maintenance expenses (exclusive of depreciation shown separately below)

154.3

158.4

Depreciation expense

123.0

113.1

General and administrative expenses

11.5

8.1

Total costs and expenses

288.8

279.6

Income from operations

373.6

286.2

Interest expense, net

1.3

1.4

Net income

372.3

284.8

Less: Net income attributable to noncontrolling interest

301.5

175.4

Net income attributable to Hess Midstream Partners LP

70.8

41.2

Less: General partner's interest in net income attributable to Hess Midstream Partners LP

1.7

0.8

Limited partners' interest in net income attributable to Hess Midstream Partners LP

$ 69.1

$ 40.4

Cash distributions declared per unit

^[1]

$ 1.4061

$ 0.9028

Predecessor

Revenues and other income

Affiliate services

$ 509.8

Type of Revenue [Extensible List]

hesm:AffiliateServicesMember

Total revenues and other income

$ 509.8

Costs and expenses

Operating and maintenance expenses (exclusive of depreciation shown separately below)

193.4

Depreciation expense

99.7

General and administrative expenses

10.4

Total costs and expenses

303.5

Income from operations

206.3

Interest expense, net

1.4

Net income

$ 68.2

$ 204.9

Common Units

Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):

Net income attributable to Hess Midstream Partners per limited partner unit

$ 1.27

$ 0.75

Weighted average limited partner units outstanding, Basic:

Units outstanding, Basic

27.3

26.9

Weighted average limited partner units outstanding, Diluted:

Units outstanding, Diluted

27.4

26.9

Subordinated Units

Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):

Net income attributable to Hess Midstream Partners per limited partner unit

$ 1.27

$ 0.75

Weighted average limited partner units outstanding, Basic:

Units outstanding, Basic

27.3

26.9

Weighted average limited partner units outstanding, Diluted:

Units outstanding, Diluted

27.3

26.9

[1]	Represents cash distributions declared during the month following the end of each respective quarterly period. See Note 13, Subsequent Events.

CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL - Partners' Capital - USD ($) $ in Millions	Total	Limited Partner Common Unitholders - Public	Limited Partner Common Unitholders - Affiliate	Limited Partner Subordinated Unitholders - Affiliate	General Partner	Noncontrolling Interest	Net Parent Investment Predecessor
Balance, beginning of period (Predecessor) at Dec. 31, 2015	$ 2,098.8						$ 2,098.8
Net income \| Predecessor	204.9						204.9
Contribution of property, plant and equipment \| Predecessor	58.4						58.4
Other contributions from (distributions to) parent, net \| Predecessor	(123.7)						(123.7)
Balance, end of period (Predecessor) at Dec. 31, 2016	2,238.4						2,238.4
Net income \| Predecessor	68.2						68.2
Net income	284.8
Other contributions from parent, net, prior to the IPO on April 10, 2017 \| Predecessor	225.0						225.0
Contribution of net assets to Hess Midstream Partners LP \| Predecessor			$ 134.6	$ 357.2	$ 14.6	$ 2,025.2	$ (2,531.6)
IPO proceeds, net of underwriters' discounts	365.5	$ 365.5
Offering costs	(10.7)	(10.7)
Distribution of IPO proceeds	(349.5)		(95.7)	(253.8)
Net income subsequent to the IPO on April 10, 2017	216.6	12.6	7.6	20.2	0.8	175.4
Unit-based compensation	0.2	0.2
Distributions to unitholders	(32.3)	(9.9)	(6.0)	(15.8)	(0.6)
Distributions to noncontrolling interest	(244.6)					(244.6)
Contributions from noncontrolling interest	78.5					78.5
Balance, end of period at Dec. 31, 2017	2,555.3	357.7	40.5	107.8	14.8	2,034.5
Net income	372.3	21.6	13.0	34.5	1.7	301.5
Unit-based compensation	0.9	0.9
Distributions to unitholders	(75.7)	(23.1)	(14.0)	(37.0)	(1.6)
Distributions to noncontrolling interest	(199.2)					(199.2)
Contributions from noncontrolling interest	57.3					57.3
Balance, end of period at Dec. 31, 2018	$ 2,710.9	$ 357.1	$ 39.5	$ 105.3	$ 14.9	$ 2,194.1

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 372.3	$ 284.8
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense	123.0	113.1
Amortization of deferred financing costs	1.0	0.6
Unit-based compensation expense	0.9	0.2	$ 0.0
Changes in assets and liabilities:
Accounts receivable – affiliate	(3.2)	(15.2)
Other current and noncurrent assets	1.6	(1.7)
Accounts payable – trade	3.1	(16.6)
Accounts payable – affiliate	(6.7)	34.4
Accrued liabilities	2.7	(1.9)
Other current and noncurrent liabilities	(1.1)	2.2
Net cash provided by (used in) operating activities	493.6	399.9
Cash flows from investing activities
Payments for equity investments	(67.3)
Additions to property, plant and equipment	(235.6)	(136.4)
Net cash provided by (used in) investing activities	(302.9)	(136.4)
Cash flows from financing activities
Cash distributions to parent prior to the IPO on April 10, 2017		(95.3)
Cash contributions from parent prior to the IPO on April 10, 2017		67.1
IPO proceeds, net of underwriters' discounts		365.5
Cash offering costs		(2.1)
Distribution of IPO proceeds to Hess and GIP		(349.5)
Financing costs		(3.9)
Distributions to unitholders	(75.7)	(32.3)
Distributions to noncontrolling interest	(199.2)	(244.6)
Contributions from noncontrolling interest	57.3	78.5
Net cash provided by (used in) financing activities	(217.6)	(216.6)
Increase (decrease) in cash and cash equivalents	(26.9)	46.9
Cash and cash equivalents, beginning of period	47.2	0.3
Cash and cash equivalents, end of period	$ 20.3	47.2	0.3
Supplemental disclosure of non-cash investing and financing activities:
Contribution to settle accounts payable – affiliate		253.2
Removal of historical capitalized offering costs		8.6
Predecessor
Cash flows from operating activities
Net income		68.2	204.9
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense			99.7
Amortization of deferred financing costs			1.1
Changes in assets and liabilities:
Accounts receivable – affiliate			5.9
Other current and noncurrent assets			2.1
Accounts payable – trade			(12.7)
Accounts payable – affiliate			87.5
Accrued liabilities			2.4
Other current and noncurrent liabilities			(3.6)
Net cash provided by (used in) operating activities			387.3
Cash flows from investing activities
Additions to property, plant and equipment			(263.6)
Net cash provided by (used in) investing activities			(263.6)
Cash flows from financing activities
Cash distributions to parent prior to the IPO on April 10, 2017			(306.9)
Cash contributions from parent prior to the IPO on April 10, 2017			183.2
Net cash provided by (used in) financing activities			(123.7)
Cash and cash equivalents, beginning of period		$ 0.3	0.3
Cash and cash equivalents, end of period			0.3
Supplemental disclosure of non-cash investing and financing activities:
Contribution of property, plant and equipment			$ 58.4

Summary of Significant Accounting Policies and Basis of Presentation

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies and Basis of Presentation

Note 2. Summary of Significant Accounting Policies and Basis of Presentation

Predecessor Presentation. The accompanying financial statements for periods prior to the IPO on April 10, 2017, represent the financial position, results of operations, cash flows and net parent investment of the Predecessor on a combined basis and include 100% of the operations of Gathering Opco, HTGP Opco, Logistics Opco, Mentor Storage Terminal and Hess Midstream Partners LP. These Contributed Businesses are presented based on Hess’s historical cost in the Predecessor financial statements as entities being under common control. All intercompany transactions and accounts within the Predecessor have been eliminated.

The Predecessor’s parent used a centralized approach to the cash management and financing of its operations. Cash generated and used in the Predecessor’s operations was transferred to the parent on a regular basis; therefore, the Predecessor did not have a cash balance as of December 31, 2016. We have reflected cash management and financing activities performed by the parent as a component of Other contributions from parent, net on the accompanying consolidated statements of changes in partners’ capital.

Consolidation. The consolidated financial statements for the period subsequent to the IPO on April 10, 2017, include our accounts and those of our wholly-owned subsidiaries on a consolidated basis. We consolidate the accounts of entities over which we have a controlling financial interest through our ownership of the general partner or the majority voting interests of the entity. We consolidate the activities of Gathering Opco, HTGP Opco and Logistics Opco, which qualify as variable interest entities (“VIE”) under the U.S. generally accepted accounting principles. We have concluded that we are the primary beneficiary of each VIE, as defined in the accounting standards, since we have the power through our general partner interests to direct those activities that most significantly impact the economic performance of the Contributed Businesses and have a right to receive benefits and an obligation to absorb losses that could potentially be significant. The conclusion was based on a qualitative analysis that considered the governance structure, the voting rights established between the members which provide us the ability to control the operations of the Contributed Business, and the absence of substantive kick‑out or substantive participating rights of limited partners over the general partners. All financial statement activities associated with VIEs are captured within gathering, processing and storage, and terminaling and export segments (see Note 12, Segments). We reflect a noncontrolling interest representing the retained interest owned by Hess Infrastructure Partners in the Contributed Businesses in the consolidated financial statements of the Partnership. All intercompany transactions and balances within the Partnership have been eliminated.

Use of Estimates. We prepare our consolidated financial statements in conformity with the U.S. generally accepted accounting principles (“GAAP”), which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the years presented. Changes in facts and circumstances may result in revised estimates and actual results could differ from those estimates.

Cash and Cash Equivalents. Cash equivalents consist of highly liquid investments, which are readily convertible into cash and have maturities of three months or less when acquired.

Accounts Receivable. We record affiliate accounts receivable upon performance of services to affiliated companies. Generally, we receive payments from affiliated companies on a monthly basis, shortly after performance of services. There were no doubtful accounts written off, nor have we provided an allowance for doubtful accounts, as of December 31, 2018 and 2017.

Property, Plant and Equipment. Property, plant and equipment are stated at the lower of historical cost less accumulated depreciation subject to the results of impairment testing. We capitalize all construction-related direct labor and material costs, as well as indirect construction costs. Indirect construction costs include general engineering, taxes and the cost of funds used during construction. Costs, including complete asset replacements and enhancements or upgrades that increase the original efficiency, productivity or capacity of property, plant and equipment, are also capitalized. The costs of repairs, minor replacements and other projects, which do not increase the original efficiency, productivity or capacity of property, plant and equipment, are expensed as incurred.

Capitalization of Interest. Interest charges from borrowings are capitalized on material projects using the weighted average cost of outstanding borrowings until the project is substantially complete and ready for its intended use. Capitalized interest is depreciated over the useful lives of the assets in the same manner as the depreciation of the underlying assets.

Impairment of Long‑Lived Assets. We review long-lived assets for impairment whenever events or changes in business circumstances indicate the net book values of the assets may not be recoverable. Impairment is indicated when the undiscounted cash flows estimated to be generated by those assets are less than the assets’ net book value. Undiscounted cash flows are based on identifiable cash flows that are largely independent of the cash flows of other assets and liabilities. If impairment occurs, a loss is recognized for the difference between the fair value and net book value. Such fair value is generally determined by discounting anticipated future net cash flows, an income valuation approach, or by a market-based valuation approach, which are Level 3 fair value measurements. Factors that indicate potential impairment include a significant decrease in the market value of the asset, operating or cash flow losses associated with the use of the asset, and a significant change in the asset’s physical condition or use. No impairments of long‑lived assets were recorded during the years ended December 31, 2018, 2017 and 2016.

Equity Investments. We account for our investment in LM4 under the equity method of accounting, as we do not control, but have a significant influence over, its operations. As of December 31, 2018, we contributed $67.3 million of cash for our gross interest in LM4. We do not have a basis difference between the amount at which the investment is carried and the amount of underlying equity in net assets of the investee.

Deferred Financing Costs. We capitalize debt issuance costs and fees incurred related to the procurement of our revolving credit facility. We amortize such costs as additional interest expense over the life of the credit agreement using the straight-line method, which approximates the effective interest method. Unamortized deferred financing costs related to our revolving credit facility are presented in Other noncurrent assets (2018: $2.2 million, 2017: $3.2 million) in the accompanying consolidated balance sheets.

Asset Retirement Obligations. We have recorded legal obligations to remove and dismantle long-lived assets. We recognize a liability for the fair value of legally required asset retirement obligations associated with long-lived assets in the period in which the retirement obligations are incurred. In addition, the fair value of any legally required conditional asset retirement obligations is recorded if the liability can be reasonably estimated. The associated asset retirement costs are capitalized as part of the carrying amount of the long-lived assets. Accretion expense is included in Depreciation expense in the consolidated statements of operations. We have not incurred significant asset retirement obligations.

Net Parent Investment. In the accompanying consolidated statements of changes in partners’ capital, Net parent investment represents our parent’s historical investment in us, our accumulated net earnings through April 10, 2017, and the net effect of transactions with Hess or Hess Infrastructure Partners.

Revenue Recognition—Contracts with Customers. We earn substantially all of our revenues by charging fees for gathering, compressing and processing natural gas and fractionating NGLs; gathering, terminaling, loading and transporting crude oil and NGLs, and storing and terminaling propane. We do not own or take title to the volumes that we handle. Effective January 1, 2014, we entered into i) gas gathering, ii) crude oil gathering, iii) gas processing and fractionation, iv) storage services, and v) terminal and export services fee‑based commercial agreements with certain subsidiaries of Hess. Our responsibilities to provide each of the above services under each of the commercial agreements are considered separate, distinct performance obligations.

We recognize revenues for each performance obligation under our commercial agreements over‑time as services are rendered using the output method, measured using the amount of volumes serviced during the period. The minimum volume commitments are subject to fluctuation based on nominations covering substantially all of Hess’s production and projected third-party volumes that will be purchased in the Bakken. As the minimum volume commitments are subject to fluctuation, and these commercial agreements contain fee inflation escalators and fee recalculation mechanisms, substantially all of the transaction price, as this term is defined in ASC 606, is variable at inception of each of the commercial agreements. As the variability is resolved prior to the recognition of revenue, we do not apply a constraint to the transaction price at the inception of the commercial agreements. We elected the practical expedient to recognize revenue in the amount to which we have a right to invoice as permitted under ASC 606. Due to this election and as the transaction price allocated to our unsatisfied performance obligations is entirely variable, we have elected the exemption provided by ASC 606 from the disclosure of revenue recognizable in future periods as our unsatisfied performance obligations are fulfilled. There are no significant financing components in any of our commercial agreements.

The minimum volumes that Hess provides to our assets under our commercial agreements include dedicated production covering substantially all of Hess’s existing and future owned or controlled production in the Bakken and projected third-party volumes owned or controlled by Hess through dedicated third-party contracts. If Hess delivers volumes less than the applicable minimum volume commitments under our commercial agreements during any quarter, Hess is obligated to pay us a shortfall fee equal to the volume deficiency multiplied by the related gathering, processing and/or terminaling fee, as applicable. Our responsibility to stand-ready to service a minimum volume over each quarterly commitment period represents a separate, distinct performance obligation. Currently, and for the remainder of the Initial Term of each commercial agreement as described in Note 3 below, volume deficiencies are measured quarterly and recognized as revenue in the same period, as any associated shortfall payments are not subject to future reduction or offset. During the Secondary Term of each commercial agreement as described in Note 3 below, Hess will be entitled to receive a credit, calculated in barrels or Mcf, as applicable, with respect to the amount of any shortfall fee paid by Hess, which will initially be reported in deferred revenue. Hess may apply such credit against the fees payable for any volumes delivered to us under the applicable agreement in excess of Hess’s nominated volumes up to four quarters after such credit is earned. Unused credits by Hess will be recognized as revenue when they expire after four quarters. However, Hess will not be entitled to receive any such credit with respect to crude oil terminaling services under our terminal and export services agreement.

Our revenues also include pass‑through third‑party rail transportation costs and electricity fees for which we recognize revenues in an amount equal to the costs.

Refer to Note 12, Segments, for the presentation of our revenues on a disaggregated basis. All Affiliate services revenue which reflects activity associated with our commercial agreements with Hess, represents revenue from contracts with customers under the scope of ASC 606.

Depreciation Expense. We calculate depreciation using the straight-line method based on the estimated useful lives after considering salvage values of our assets. Depreciation lives range from 12 to 35 years. However, factors such as maintenance levels, economic conditions impacting the demand for these assets, and regulatory or environmental requirements could cause us to change our estimates, thus impacting the future calculation of depreciation.

Unit‑Based Compensation. Unit‑based compensation issued to the officers, directors and employees of our general partner is recorded at grant‑date fair value. Expense is recognized on a straight‑line basis over the vesting period of the award and is included in General and administrative expenses in the accompanying consolidated statements of operations. Forfeitures are recognized as they occur.

Income Taxes. We are not a separate taxable entity for U.S. Federal and state income tax purposes; therefore, we do not provide for income tax benefit or expense. Each partner is subject to income taxes on its share of the Partnership’s earnings.

Comprehensive Income. We have not reported comprehensive income since there were no items of other comprehensive income (loss) during the years ended December 31, 2018, 2017 and 2016.

Net Income Per Limited Partner Unit. We have identified the general partner interest and the incentive distribution rights ("IDRs") as participating securities and compute income per unit using the two‑class method under which net income per unit is calculated for common units and participating securities considering both distributions declared and participation rights in undistributed earnings as if all such earnings had been distributed during this period. Net income per unit applicable to limited partners, including subordinated unitholders, is computed by dividing limited partners' interest in net income, after deducting the general partner's 2% interest and incentive distributions, by the weighted‑average number of outstanding common and subordinated units.

Environmental and Legal Contingencies. We accrue and expense environmental costs on an undiscounted basis to remediate existing conditions related to past operations when the future costs are probable and reasonably estimable.

In the ordinary course of business, the Partnership is from time to time party to various judicial and administrative proceedings. We regularly assess the need for accounting recognition or disclosure of these contingencies. In the case of a known contingency, we accrue a liability when the loss is probable and the amount is reasonably estimable. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued.

Fair Value Measurements. We measure assets and liabilities requiring fair value presentation using an exit price (i.e., the price that would be received to sell an asset or paid to transfer a liability) and disclose such amounts according to the level of valuation inputs under the following hierarchy:

Level 1: Quoted prices in an active market for identical assets or liabilities.

Level 2: Inputs other than quoted prices that are directly or indirectly observable.

Level 3: Unobservable inputs that are significant to the fair value of assets or liabilities.

The classification of an asset or liability within the fair value measurement hierarchy is based on the lowest level of input significant to its fair value.

There were no nonrecurring fair value measurements during the years ended December 31, 2018 and 2017. We had other short‑term financial instruments, primarily cash and cash equivalents, accounts receivable and accounts payable, for which the carrying value approximated their fair value as of December 31, 2018 and 2017.

New Accounting Pronouncements: In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2014-09, Revenue from Contracts with Customers, as a new Accounting Standards Codification (ASC) Topic, ASC 606. We adopted ASC 606 as of January 1, 2018 using the modified retrospective method that requires application of the new standard prospectively from the date of adoption. The adoption of ASC 606 did not have a material impact on the timing or amount of revenue recognition for our uncompleted contracts at January 1, 2018 based on the requirements of the standard and, as a result, no cumulative effect adjustment was required to be recorded to our partners’ capital balance as of January 1, 2018. Accounts receivable from contracts with customers are presented separately in the consolidated balance sheet with the prior year balance recast to conform to the current period presentation.

In February 2016, the FASB issued ASU 2016 02, Leases, as a new ASC Topic, ASC 842. The new standard supersedes ASC 840 and will require the recognition of right-of-use assets and lease liabilities for all leases with lease terms greater than one year, including leases currently treated as operating leases under ASC 840. ASC 842 is effective for us beginning in the first quarter of 2019, with early adoption permitted. We have elected to adopt ASC 842 on January 1, 2019 using the modified retrospective method which allows application of the new standard prospectively from the date of adoption with a cumulative effect adjustment, if any, recorded to partners’ capital at the date of adoption. Accordingly, comparative financial statements for periods prior to the adoption date of ASC 842 will not be affected. In addition, we have elected to apply the ‘package’ of practical expedients allowing us to avoid reassessing whether existing contracts are (or contain) leases, whether the lease classification for existing leases would differ under ASC 842, and whether initial direct costs incurred for existing leases are capitalizable under ASC 842. Finally, we have elected to apply the practical expedient allowing us to avoid reassessing land easements that were not previously accounted for as leases under ASC 840. We have not elected the ‘hindsight’ practical expedient when determining lease term. We have completed our implementation plan to adopt ASC 842, but we continue to monitor standard setting activity and our internal controls to comply with the accounting and disclosure requirements. Implementation of the new standard on January 1, 2019 is not expected to have a material impact on our consolidated financial statements.

Related Party Transactions

12 Months Ended

Dec. 31, 2018

Related Party Transactions

Note 3. Related Party Transactions

We are part of the consolidated operations of Hess, and substantially all of our revenues as shown on the accompanying consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 were derived from transactions with Hess and its affiliates, although we plan to provide our services to third parties in the future. Hess also provides substantial operational and administrative services to us in support of our assets and operations.

Commercial Agreements

Effective January 1, 2014, we entered into i) gas gathering, ii) crude oil gathering, iii) gas processing and fractionation, iv) storage services, and v) terminal and export services fee‑based commercial agreements with certain subsidiaries of Hess. Under these commercial agreements, we provide gathering, compression, processing, fractionation, storage, terminaling, loading and transportation services to Hess, for which we receive a fee per barrel of crude oil, Mcf of natural gas, or Mcf equivalent of NGLs, as applicable, delivered during each month, and Hess is obligated to provide us with minimum volumes of crude oil, natural gas and NGLs. These agreements also include inflation escalators and fee recalculation mechanisms that allow fees to be adjusted annually.

On September 17, 2018, we amended and restated our gas gathering and gas processing and fractionation agreements with Hess to enable us to provide certain services to Hess in respect of volumes to be delivered to and processed at the LM4 plant. Effective January 1, 2019, Hess will pay us a combined processing fee per Mcf of natural gas, or Mcf equivalent of NGLs, as applicable, for aggregate volumes processed at LM4 and the Tioga Gas Plant. Except with regard to a certain gathering sub-system as described below, each of our commercial agreements with Hess retains its initial 10‑year term (“Initial Term”) and we have the unilateral right to extend each commercial agreement for one additional 10‑year term (“Secondary Term”). The amended and restated gas gathering agreement also extends the Initial Term of the gathering agreement with respect to a certain gathering sub-system by 5 years to provide for a 15-year Initial Term and decreases the Secondary Term for that gathering sub-system by 5 years to provide for a 5-year Secondary Term. In addition, the fee recalculation mechanism continues to apply to the amended and restated agreements and, effective January 1, 2019, will incorporate the revenues received and expected to be received by Hess from sourcing third-party dedicated production in order to further align the interests of us and Hess in promoting the growth of third-party volumes on our Bakken assets.

For the years ended December 31, 2018, 2017 and 2016, approximately 100% of our revenues were attributable to our fee‑based commercial agreements with Hess, including revenues from third‑party volumes contracted with Hess and delivered to us under these agreements. Together with Hess, we are pursuing strategic relationships with third-party producers and other midstream companies with operations in the Bakken in order to maximize our utilization rates.

During the year ended December 31, 2018, we earned $47.5 million of minimum volume shortfall fee payments (2017: $61.6 million, 2016: $36.5 million). In addition, during the year ended December 31, 2018, we recognized, as part of the affiliate revenues, $16.8 million of reimbursements from Hess related to third‑party rail transportation costs (2017: $17.0 million, 2016: $31.7 million). Finally, during the year ended December 31, 2018, we recognized, as part of affiliate revenues, $27.2 million of reimbursements from Hess related to electricity fees (2017: $24.9 million, 2016: $24.1 million). The related third-party rail transportation costs and electricity fees were included in Operating and maintenance expenses in the accompanying consolidated statements of operations.

Omnibus and Employee Secondment Agreements

In connection with the Partnership’s IPO in April 2017, we entered into an omnibus agreement with Hess and Hess Infrastructure Partners under which we pay Hess on a monthly basis an amount equal to the total allocable costs of Hess’s employees and contractors, subcontractors or other outside personnel engaged by Hess and its subsidiaries to the extent such employees and outside personnel perform operational and administrative services for us in support of our assets, plus a specified percentage markup of such amount depending on the type of service provided, as well as an allocable share of direct costs of providing these services. The omnibus agreement also includes our right of first offer to acquire certain of Hess Infrastructure Partners’ midstream assets, including Hess Infrastructure Partners’ retained interests in the Contributed Businesses and Hess Infrastructure Partners’ indemnification of us for certain matters, including certain pre‑closing environmental, title and tax matters. Pursuant to the omnibus agreement, we agreed to indemnify Hess Infrastructure Partners for certain post‑closing matters under this agreement, including certain post‑closing environmental liabilities.

In connection with the Partnership’s IPO, we also entered into an employee secondment agreement with Hess under which certain employees of Hess are seconded to our general partner to provide services with respect to our assets and operations, including executive oversight, business and corporate development, unitholder and investor relations, communications and public relations, routine and emergency maintenance and repair services, routine operational services, routine administrative services, construction services, and such other operational, commercial and business services that are necessary to develop and execute the Partnership’s business strategy. On a monthly basis, we pay a secondment fee to Hess that is intended to cover and reimburse Hess for the total costs actually incurred by Hess and its affiliates in connection with employing the seconded employees to the extent such total costs are attributable to the provision of services with respect to the Partnership’s assets and operations.

For the years ended December 31, 2018, 2017 and 2016, we had the following charges from Hess, including for the services agreements described above and expenses directly charged and allocated to the Predecessor. The classification of these charges between operating and maintenance expenses and general and administrative expenses is based on the fundamental nature of the services being performed for our operations.

	Year Ended December 31,
	2018		2017		2016
(in millions)					Predecessor
Operating and maintenance expenses	$	48.0	$	56.6	$	62.5
General and administrative expenses		7.1		5.9		10.4
Total	$	55.1	$	62.5	$	72.9

Contribution Agreement

In connection with the Partnership’s IPO in April 2017, we entered into a contribution, conveyance and assumption agreement, under which Hess Infrastructure Partners agreed to bear the cost of certain maintenance capital projects associated with the Contributed Businesses. During the year ended December 31, 2018, Hess Infrastructure Partners contributed $3.5 million to us related to the reimbursement for those maintenance capital projects (2017: $16.9 million, 2016: zero). This provision of the agreement is expiring in April 2019, the second anniversary of the Partnership’s IPO.

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property, Plant and Equipment

Note 4. Property, Plant and Equipment

Property, plant and equipment, at cost, is as follows:

	Estimated useful lives	December 31, 2018			December 31, 2017
(in millions, except for number of years)
Gathering assets
Pipelines	22 years	$	1,003.9		$	890.8
Compressors, pumping stations and terminals	22 to 25 years		557.5			535.5
Gas plant assets
Pipelines, pipes and valves	22 to 25 years		460.0			460.0
Equipment	12 to 30 years		428.2			428.2
Buildings	35 years		182.3			182.3
Processing and fractionation facilities	25 years		185.5			158.4
Logistics facilities and railcars	20 to 25 years		385.8			371.1
Storage facilities	20 to 25 years		19.5			19.5
Other	20 to 25 years		10.7			9.2
Construction-in-progress	N/A		157.3			69.5
Total property, plant and equipment, at cost			3,390.7			3,124.5
Accumulated depreciation			(726.6	)		(604.0	)
Property, plant and equipment, net		$	2,664.1		$	2,520.5

Unit-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Unit-Based Compensation

Note 8. Unit-Based Compensation

In 2017, the Partnership adopted the Hess Midstream Partners LP 2017 Long‑Term Incentive Plan (the “LTIP”). Awards under the LTIP are available for officers, directors and employees of our general partner or its affiliates, and any individuals who perform services for the Partnership. The LTIP provides the Partnership with the flexibility to grant unit awards, restricted units, phantom units, unit options, unit appreciation rights, distribution equivalent rights, profits interest units and other unit‑based awards. The LTIP initially limits the number of common units that may be delivered pursuant to vested awards to 3,000,000 common units.

Under the LTIP, we granted awards of phantom units with distribution equivalent rights to certain officers, employees and directors. These phantom units and distribution equivalent rights vest ratably over a three‑year period for officers and employees, and vest after one year for directors. Each phantom unit represents the right to receive one of our common units upon vesting (or an equivalent amount of cash). Cash distributions on the phantom units accumulate and are paid upon vesting. Fair value of phantom units is based on the fair value of the Partnership’s common units on the grant date.

Unit‑based award activity for the year ended December 31, 2018 was as follows:

				Weighted Average
				Award Date
	Number of Units			Fair Value
Outstanding and unvested units at December 31, 2017		44,127		$	22.85
Granted		90,594			20.51
Forfeited		(3,107	)		21.73
Vested		(17,377	)		22.63
Outstanding and unvested units at December 31, 2018		114,237		$	21.06



(in millions)	2018		2017		2016
Fair value of units granted	$	1.9	$	1.0		*
Fair value of units vested	$	0.4	$	-		*

*Information is not applicable for the period prior to the Partnership’s IPO on April 10, 2017.

During the year ended December 31, 2018, we recognized compensation expense related to the outstanding awards of $0.9 million (2017: $0.2 million, 2016: zero). As of December 31, 2018, $1.6 million of compensation cost related to our unvested phantom units awarded under the LTIP remains to be recognized over an expected weighted‑average period of 1.9 years.

Net Income per Limited Partner Unit

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Net Income per Limited Partner Unit

Note 9. Net Income per Limited Partner Unit

Net income per limited partner unit is computed by dividing the respective limited partners’ interest in net income attributable to Hess Midstream Partners LP by the weighted average number of common and subordinated units outstanding. Because we have more than one class of participating securities, we use the two‑class method when calculating net income per limited partner unit. The classes of participating securities include common units, subordinated units, general partner units and incentive distribution rights.

Net income per limited partner unit is only calculated for the periods subsequent to the IPO as no units were outstanding prior to April 10, 2017. The following table illustrates the Partnership’s calculation of net income per limited partner unit:

	Year Ended
(in millions, except per unit amounts)	December 31, 2018		December 31, 2017
Net income	$	372.3	$	284.8
Less: Net income prior to the IPO on April 10, 2017		-		68.2
Less: Net income attributable to noncontrolling interest		301.5		175.4
Net income attributable to Hess Midstream Partners LP		70.8		41.2
Less: General partner interest in net income attributable to Hess Midstream Partners LP		1.7		0.8
Limited partners' interest in net income attributable to Hess Midstream Partners LP	$	69.1	$	40.4
Common unitholders' interest in net income attributable to Hess Midstream Partners LP	$	34.6	$	20.2
Subordinated unitholders' interest in net income attributable to Hess Midstream Partners LP	$	34.5	$	20.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Common (basic and diluted)	$	1.27	$	0.75
Subordinated (basic and diluted)	$	1.27	$	0.75
Weighted average number of limited partner units outstanding:
Basic:
Common		27.3		26.9
Subordinated		27.3		26.9
Diluted:
Common		27.4		26.9
Subordinated		27.3		26.9

Segments

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segments

Note 12. Segments

Our operations are located in the United States and are organized into three reportable segments: (i) gathering, (ii) processing and storage and (iii) terminaling and export. Our reportable segments comprise the structure used by our Chief Operating Decision Maker (“CODM”) to make key operating decisions and assess performance. These segments are strategic business units with differing products and services. The accounting policies of the segments are identical to those described in Note 2, Summary of Significant Accounting Policies and Basis of Presentation. Our CODM evaluates the segments’ operating performance based on multiple measures including Adjusted EBITDA, defined as earnings before interest, income tax, depreciation and amortization, as further adjusted for other non‑cash, non‑recurring items, if applicable.

Gathering. Our gathering segment consists of the following assets:

•

Natural Gas Gathering and Compression. A natural gas gathering and compression system located primarily in McKenzie, Williams and Mountrail Counties, North Dakota, connecting Hess and third‑party owned or operated wells to the Tioga Gas Plant, LM4 gas processing plant, when completed, and third‑party pipeline facilities. The system also includes the Hawkeye Gas Facility, which was placed into service during the first quarter of 2017.

•

Crude Oil Gathering: A crude oil gathering system located primarily in McKenzie, Williams and Mountrail Counties, North Dakota, connecting Hess and third party owned or operated wells to the Ramberg Terminal Facility, the Tioga Rail Terminal and the Johnson’s Corner Header System. The system also includes the Hawkeye Oil Facility, which was placed into service during the fourth quarter of 2017.

Processing and Storage. Our processing and storage segment consists of the following assets:

•

Tioga Gas Plant (TGP). A natural gas processing and fractionation plant located in Tioga, North Dakota.

•

Mentor Storage Terminal. A propane storage cavern and rail and truck loading and unloading facility located in Mentor, Minnesota.

•

Equity Investment in LM4 Joint Venture. A 50% equity method investment in LM4 joint venture that owns a natural gas processing plant located in McKenzie County, North Dakota, which was still under construction as of December 31, 2018.

Terminaling and Export. Our terminaling and export segment consists of the following assets:

•

Ramberg Terminal Facility. A crude oil pipeline and truck receipt terminal located in Williams County, North Dakota that is capable of delivering crude oil into an interconnecting pipeline for transportation to the Tioga Rail Terminal and to multiple third‑party pipelines and storage facilities.

•

Tioga Rail Terminal. A crude oil and NGL rail loading terminal in Tioga, North Dakota that is connected to the Tioga Gas Plant, the Ramberg Terminal Facility and our crude oil gathering system.

•

Crude Oil Rail Cars. A total of 550 crude oil rail cars, constructed to the most recent DOT‑117 safety standards, which we operate as unit trains consisting of approximately 100 to 110 crude oil rail cars.

•

Johnson’s Corner Header System. An approximately six‑mile crude oil pipeline header system located in McKenzie County, North Dakota that receives crude oil by pipeline from Hess and third parties and delivers crude oil to third‑party interstate pipeline systems. The Johnson’s Corner Header System commenced operations in the third quarter of 2017.

The following tables reflect certain financial data for each reportable segment:

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Year Ended December 31, 2018
Revenues and other income	$	324.9	$	251.4	$	86.1	$	-		$	662.4
Net income (loss)		193.0		148.8		36.1		(5.6	)		372.3
Net income (loss) attributable to Hess Midstream Partners LP		38.4		30.7		7.3		(5.6	)		70.8
Depreciation expense		63.3		43.9		15.8		-			123.0
Interest expense		-		-		-		1.3			1.3
Adjusted EBITDA		256.3		192.7		51.9		(4.3	)		496.6
Adjusted EBITDA attributable to Hess Midstream Partners LP		51.0		39.5		10.5		(4.3	)		96.7
Capital expenditures		250.4		10.0		4.3		-			264.7

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Year Ended December 31, 2017
Revenues and other income	$	271.6	$	227.3	$	66.7	$	0.2		$	565.8
Net income (loss)		149.9		123.8		14.4		(3.3	)		284.8
Net income (loss) attributable to Hess Midstream Partners LP		23.3		18.8		2.4		(3.3	)		41.2
Depreciation expense		54.4		43.6		15.1		-			113.1
Interest expense		-		-		-		1.4			1.4
Adjusted EBITDA		204.3		167.4		29.5		(1.9	)		399.3
Adjusted EBITDA attributable to Hess Midstream Partners LP		31.5		25.1		4.6		(1.9	)		59.3
Capital expenditures		72.7		15.9		24.6		-			113.2

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP Predecessor
(in millions)
For the Year Ended December 31, 2016
Revenues and other income	$	212.8	$	196.7	$	100.3	$	-		$	509.8
Net income (loss)		96.9		92.7		16.7		(1.4	)		204.9
Depreciation expense		39.9		44.0		15.8		-			99.7
Interest expense		-		-		-		1.4			1.4
Adjusted EBITDA		136.8		136.7		32.5		-			306.0
Capital expenditures		208.3		35.4		21.2		-			264.9

Total assets for reportable segments are as follows:


	December 31, 2018		December 31, 2017
(in millions)
Gathering	$	1,467.7	$	1,280.5
Processing and Storage⁽¹⁾		1,008.6		972.8
Terminaling and Export		320.2		330.8
Interest and Other		23.2		51.0
Total assets	$	2,819.7	$	2,635.1

⁽¹⁾Includes $67.3 million of investment in equity method investees.

Supplemental Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Supplemental Quarterly Financial Information (Unaudited)

Supplemental quarterly financial information is as follows:

	2018
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
(in millions, except per unit amounts)
Revenues and other income	$	157.0	$	164.7	$	169.5	$	171.2
Income from operations	$	89.3	$	95.0	$	97.1	$	92.2
Net income	$	89.0	$	94.6	$	96.8	$	91.9
Net income attributable to Hess Midstream Partners LP	$	17.0	$	17.8	$	18.8	$	17.2
Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):
Common	$	0.30	$	0.32	$	0.34	$	0.31
Subordinated	$	0.30	$	0.32	$	0.34	$	0.31

	2017
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
(in millions, except per unit amounts)	Predecessor
Revenues and other income	$	130.3	$	138.3	$	146.7	$	150.5
Income from operations	$	63.1	$	68.6	$	76.9	$	77.6
Net income	$	63.1	$	68.1	$	76.5	$	77.1
Net income attributable to Hess Midstream Partners LP	*		$	11.4	$	15.0	$	14.8
Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):
Common	*		$	0.21	$	0.27	$	0.26
Subordinated	*		$	0.21	$	0.27	$	0.26

*Information is not applicable for the period prior to the Partnership’s IPO on April 10, 2017.

Summary of Significant Accounting Policies and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Predecessor Presentation	Predecessor Presentation. The accompanying financial statements for periods prior to the IPO on April 10, 2017, represent the financial position, results of operations, cash flows and net parent investment of the Predecessor on a combined basis and include 100% of the operations of Gathering Opco, HTGP Opco, Logistics Opco, Mentor Storage Terminal and Hess Midstream Partners LP. These Contributed Businesses are presented based on Hess’s historical cost in the Predecessor financial statements as entities being under common control. All intercompany transactions and accounts within the Predecessor have been eliminated. The Predecessor’s parent used a centralized approach to the cash management and financing of its operations. Cash generated and used in the Predecessor’s operations was transferred to the parent on a regular basis; therefore, the Predecessor did not have a cash balance as of December 31, 2016. We have reflected cash management and financing activities performed by the parent as a component of Other contributions from parent, net on the accompanying consolidated statements of changes in partners’ capital.
Consolidation	Consolidation. The consolidated financial statements for the period subsequent to the IPO on April 10, 2017, include our accounts and those of our wholly-owned subsidiaries on a consolidated basis. We consolidate the accounts of entities over which we have a controlling financial interest through our ownership of the general partner or the majority voting interests of the entity. We consolidate the activities of Gathering Opco, HTGP Opco and Logistics Opco, which qualify as variable interest entities (“VIE”) under the U.S. generally accepted accounting principles. We have concluded that we are the primary beneficiary of each VIE, as defined in the accounting standards, since we have the power through our general partner interests to direct those activities that most significantly impact the economic performance of the Contributed Businesses and have a right to receive benefits and an obligation to absorb losses that could potentially be significant. The conclusion was based on a qualitative analysis that considered the governance structure, the voting rights established between the members which provide us the ability to control the operations of the Contributed Business, and the absence of substantive kick‑out or substantive participating rights of limited partners over the general partners. All financial statement activities associated with VIEs are captured within gathering, processing and storage, and terminaling and export segments (see Note 12, Segments). We reflect a noncontrolling interest representing the retained interest owned by Hess Infrastructure Partners in the Contributed Businesses in the consolidated financial statements of the Partnership. All intercompany transactions and balances within the Partnership have been eliminated.
Use of Estimates	Use of Estimates. We prepare our consolidated financial statements in conformity with the U.S. generally accepted accounting principles (“GAAP”), which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the years presented. Changes in facts and circumstances may result in revised estimates and actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents. Cash equivalents consist of highly liquid investments, which are readily convertible into cash and have maturities of three months or less when acquired.
Accounts Receivable	Accounts Receivable. We record affiliate accounts receivable upon performance of services to affiliated companies. Generally, we receive payments from affiliated companies on a monthly basis, shortly after performance of services. There were no doubtful accounts written off, nor have we provided an allowance for doubtful accounts, as of December 31, 2018 and 2017.
Property, Plant and Equipment	Property, Plant and Equipment. Property, plant and equipment are stated at the lower of historical cost less accumulated depreciation subject to the results of impairment testing. We capitalize all construction-related direct labor and material costs, as well as indirect construction costs. Indirect construction costs include general engineering, taxes and the cost of funds used during construction. Costs, including complete asset replacements and enhancements or upgrades that increase the original efficiency, productivity or capacity of property, plant and equipment, are also capitalized. The costs of repairs, minor replacements and other projects, which do not increase the original efficiency, productivity or capacity of property, plant and equipment, are expensed as incurred.
Capitalization of Interest	Capitalization of Interest. Interest charges from borrowings are capitalized on material projects using the weighted average cost of outstanding borrowings until the project is substantially complete and ready for its intended use. Capitalized interest is depreciated over the useful lives of the assets in the same manner as the depreciation of the underlying assets.
Impairment of Long-Lived Assets	Impairment of Long‑Lived Assets. We review long-lived assets for impairment whenever events or changes in business circumstances indicate the net book values of the assets may not be recoverable. Impairment is indicated when the undiscounted cash flows estimated to be generated by those assets are less than the assets’ net book value. Undiscounted cash flows are based on identifiable cash flows that are largely independent of the cash flows of other assets and liabilities. If impairment occurs, a loss is recognized for the difference between the fair value and net book value. Such fair value is generally determined by discounting anticipated future net cash flows, an income valuation approach, or by a market-based valuation approach, which are Level 3 fair value measurements. Factors that indicate potential impairment include a significant decrease in the market value of the asset, operating or cash flow losses associated with the use of the asset, and a significant change in the asset’s physical condition or use. No impairments of long‑lived assets were recorded during the years ended December 31, 2018, 2017 and 2016.
Equity Investments	Equity Investments. We account for our investment in LM4 under the equity method of accounting, as we do not control, but have a significant influence over, its operations. As of December 31, 2018, we contributed $67.3 million of cash for our gross interest in LM4. We do not have a basis difference between the amount at which the investment is carried and the amount of underlying equity in net assets of the investee.
Deferred Financing Costs	Deferred Financing Costs. We capitalize debt issuance costs and fees incurred related to the procurement of our revolving credit facility. We amortize such costs as additional interest expense over the life of the credit agreement using the straight-line method, which approximates the effective interest method. Unamortized deferred financing costs related to our revolving credit facility are presented in Other noncurrent assets (2018: $2.2 million, 2017: $3.2 million) in the accompanying consolidated balance sheets.
Asset Retirement Obligations	Asset Retirement Obligations. We have recorded legal obligations to remove and dismantle long-lived assets. We recognize a liability for the fair value of legally required asset retirement obligations associated with long-lived assets in the period in which the retirement obligations are incurred. In addition, the fair value of any legally required conditional asset retirement obligations is recorded if the liability can be reasonably estimated. The associated asset retirement costs are capitalized as part of the carrying amount of the long-lived assets. Accretion expense is included in Depreciation expense in the consolidated statements of operations. We have not incurred significant asset retirement obligations.
Net Parent Investment	Net Parent Investment. In the accompanying consolidated statements of changes in partners’ capital, Net parent investment represents our parent’s historical investment in us, our accumulated net earnings through April 10, 2017, and the net effect of transactions with Hess or Hess Infrastructure Partners.
Revenue Recognition	Revenue Recognition—Contracts with Customers. We earn substantially all of our revenues by charging fees for gathering, compressing and processing natural gas and fractionating NGLs; gathering, terminaling, loading and transporting crude oil and NGLs, and storing and terminaling propane. We do not own or take title to the volumes that we handle. Effective January 1, 2014, we entered into i) gas gathering, ii) crude oil gathering, iii) gas processing and fractionation, iv) storage services, and v) terminal and export services fee‑based commercial agreements with certain subsidiaries of Hess. Our responsibilities to provide each of the above services under each of the commercial agreements are considered separate, distinct performance obligations. We recognize revenues for each performance obligation under our commercial agreements over‑time as services are rendered using the output method, measured using the amount of volumes serviced during the period. The minimum volume commitments are subject to fluctuation based on nominations covering substantially all of Hess’s production and projected third-party volumes that will be purchased in the Bakken. As the minimum volume commitments are subject to fluctuation, and these commercial agreements contain fee inflation escalators and fee recalculation mechanisms, substantially all of the transaction price, as this term is defined in ASC 606, is variable at inception of each of the commercial agreements. As the variability is resolved prior to the recognition of revenue, we do not apply a constraint to the transaction price at the inception of the commercial agreements. We elected the practical expedient to recognize revenue in the amount to which we have a right to invoice as permitted under ASC 606. Due to this election and as the transaction price allocated to our unsatisfied performance obligations is entirely variable, we have elected the exemption provided by ASC 606 from the disclosure of revenue recognizable in future periods as our unsatisfied performance obligations are fulfilled. There are no significant financing components in any of our commercial agreements. The minimum volumes that Hess provides to our assets under our commercial agreements include dedicated production covering substantially all of Hess’s existing and future owned or controlled production in the Bakken and projected third-party volumes owned or controlled by Hess through dedicated third-party contracts. If Hess delivers volumes less than the applicable minimum volume commitments under our commercial agreements during any quarter, Hess is obligated to pay us a shortfall fee equal to the volume deficiency multiplied by the related gathering, processing and/or terminaling fee, as applicable. Our responsibility to stand-ready to service a minimum volume over each quarterly commitment period represents a separate, distinct performance obligation. Currently, and for the remainder of the Initial Term of each commercial agreement as described in Note 3 below, volume deficiencies are measured quarterly and recognized as revenue in the same period, as any associated shortfall payments are not subject to future reduction or offset. During the Secondary Term of each commercial agreement as described in Note 3 below, Hess will be entitled to receive a credit, calculated in barrels or Mcf, as applicable, with respect to the amount of any shortfall fee paid by Hess, which will initially be reported in deferred revenue. Hess may apply such credit against the fees payable for any volumes delivered to us under the applicable agreement in excess of Hess’s nominated volumes up to four quarters after such credit is earned. Unused credits by Hess will be recognized as revenue when they expire after four quarters. However, Hess will not be entitled to receive any such credit with respect to crude oil terminaling services under our terminal and export services agreement. Our revenues also include pass‑through third‑party rail transportation costs and electricity fees for which we recognize revenues in an amount equal to the costs. Refer to Note 12, Segments, for the presentation of our revenues on a disaggregated basis. All Affiliate services revenue which reflects activity associated with our commercial agreements with Hess, represents revenue from contracts with customers under the scope of ASC 606.
Depreciation Expense	Depreciation Expense. We calculate depreciation using the straight-line method based on the estimated useful lives after considering salvage values of our assets. Depreciation lives range from 12 to 35 years. However, factors such as maintenance levels, economic conditions impacting the demand for these assets, and regulatory or environmental requirements could cause us to change our estimates, thus impacting the future calculation of depreciation.
Unit-Based Compensation	Unit‑Based Compensation. Unit‑based compensation issued to the officers, directors and employees of our general partner is recorded at grant‑date fair value. Expense is recognized on a straight‑line basis over the vesting period of the award and is included in General and administrative expenses in the accompanying consolidated statements of operations. Forfeitures are recognized as they occur.
Income Taxes	Income Taxes. We are not a separate taxable entity for U.S. Federal and state income tax purposes; therefore, we do not provide for income tax benefit or expense. Each partner is subject to income taxes on its share of the Partnership’s earnings.
Comprehensive Income	Comprehensive Income. We have not reported comprehensive income since there were no items of other comprehensive income (loss) during the years ended December 31, 2018, 2017 and 2016.
Net Income per Limited Partner Unit	Net Income Per Limited Partner Unit. We have identified the general partner interest and the incentive distribution rights ("IDRs") as participating securities and compute income per unit using the two‑class method under which net income per unit is calculated for common units and participating securities considering both distributions declared and participation rights in undistributed earnings as if all such earnings had been distributed during this period. Net income per unit applicable to limited partners, including subordinated unitholders, is computed by dividing limited partners' interest in net income, after deducting the general partner's 2% interest and incentive distributions, by the weighted‑average number of outstanding common and subordinated units.
Environmental and Legal Contingencies	Environmental and Legal Contingencies. We accrue and expense environmental costs on an undiscounted basis to remediate existing conditions related to past operations when the future costs are probable and reasonably estimable. In the ordinary course of business, the Partnership is from time to time party to various judicial and administrative proceedings. We regularly assess the need for accounting recognition or disclosure of these contingencies. In the case of a known contingency, we accrue a liability when the loss is probable and the amount is reasonably estimable. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued.
Fair Value Measurements	Fair Value Measurements. We measure assets and liabilities requiring fair value presentation using an exit price (i.e., the price that would be received to sell an asset or paid to transfer a liability) and disclose such amounts according to the level of valuation inputs under the following hierarchy: Level 1: Quoted prices in an active market for identical assets or liabilities. Level 2: Inputs other than quoted prices that are directly or indirectly observable. Level 3: Unobservable inputs that are significant to the fair value of assets or liabilities. The classification of an asset or liability within the fair value measurement hierarchy is based on the lowest level of input significant to its fair value. There were no nonrecurring fair value measurements during the years ended December 31, 2018 and 2017. We had other short‑term financial instruments, primarily cash and cash equivalents, accounts receivable and accounts payable, for which the carrying value approximated their fair value as of December 31, 2018 and 2017.
New Accounting Pronouncements	New Accounting Pronouncements: In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2014-09, Revenue from Contracts with Customers, as a new Accounting Standards Codification (ASC) Topic, ASC 606. We adopted ASC 606 as of January 1, 2018 using the modified retrospective method that requires application of the new standard prospectively from the date of adoption. The adoption of ASC 606 did not have a material impact on the timing or amount of revenue recognition for our uncompleted contracts at January 1, 2018 based on the requirements of the standard and, as a result, no cumulative effect adjustment was required to be recorded to our partners’ capital balance as of January 1, 2018. Accounts receivable from contracts with customers are presented separately in the consolidated balance sheet with the prior year balance recast to conform to the current period presentation. In February 2016, the FASB issued ASU 2016 02, Leases, as a new ASC Topic, ASC 842. The new standard supersedes ASC 840 and will require the recognition of right-of-use assets and lease liabilities for all leases with lease terms greater than one year, including leases currently treated as operating leases under ASC 840. ASC 842 is effective for us beginning in the first quarter of 2019, with early adoption permitted. We have elected to adopt ASC 842 on January 1, 2019 using the modified retrospective method which allows application of the new standard prospectively from the date of adoption with a cumulative effect adjustment, if any, recorded to partners’ capital at the date of adoption. Accordingly, comparative financial statements for periods prior to the adoption date of ASC 842 will not be affected. In addition, we have elected to apply the ‘package’ of practical expedients allowing us to avoid reassessing whether existing contracts are (or contain) leases, whether the lease classification for existing leases would differ under ASC 842, and whether initial direct costs incurred for existing leases are capitalizable under ASC 842. Finally, we have elected to apply the practical expedient allowing us to avoid reassessing land easements that were not previously accounted for as leases under ASC 840. We have not elected the ‘hindsight’ practical expedient when determining lease term. We have completed our implementation plan to adopt ASC 842, but we continue to monitor standard setting activity and our internal controls to comply with the accounting and disclosure requirements. Implementation of the new standard on January 1, 2019 is not expected to have a material impact on our consolidated financial statements.

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Components of Property, Plant and Equipment

Property, plant and equipment, at cost, is as follows:

	Estimated useful lives	December 31, 2018			December 31, 2017
(in millions, except for number of years)
Gathering assets
Pipelines	22 years	$	1,003.9		$	890.8
Compressors, pumping stations and terminals	22 to 25 years		557.5			535.5
Gas plant assets
Pipelines, pipes and valves	22 to 25 years		460.0			460.0
Equipment	12 to 30 years		428.2			428.2
Buildings	35 years		182.3			182.3
Processing and fractionation facilities	25 years		185.5			158.4
Logistics facilities and railcars	20 to 25 years		385.8			371.1
Storage facilities	20 to 25 years		19.5			19.5
Other	20 to 25 years		10.7			9.2
Construction-in-progress	N/A		157.3			69.5
Total property, plant and equipment, at cost			3,390.7			3,124.5
Accumulated depreciation			(726.6	)		(604.0	)
Property, plant and equipment, net		$	2,664.1		$	2,520.5

Net Income per Limited Partner Unit (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Schedule of Net Income per Limited Partner Unit

	Year Ended
(in millions, except per unit amounts)	December 31, 2018		December 31, 2017
Net income	$	372.3	$	284.8
Less: Net income prior to the IPO on April 10, 2017		-		68.2
Less: Net income attributable to noncontrolling interest		301.5		175.4
Net income attributable to Hess Midstream Partners LP		70.8		41.2
Less: General partner interest in net income attributable to Hess Midstream Partners LP		1.7		0.8
Limited partners' interest in net income attributable to Hess Midstream Partners LP	$	69.1	$	40.4
Common unitholders' interest in net income attributable to Hess Midstream Partners LP	$	34.6	$	20.2
Subordinated unitholders' interest in net income attributable to Hess Midstream Partners LP	$	34.5	$	20.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Common (basic and diluted)	$	1.27	$	0.75
Subordinated (basic and diluted)	$	1.27	$	0.75
Weighted average number of limited partner units outstanding:
Basic:
Common		27.3		26.9
Subordinated		27.3		26.9
Diluted:
Common		27.4		26.9
Subordinated		27.3		26.9

Segments (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Financial Data for Each Reportable Segment

The following tables reflect certain financial data for each reportable segment:

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Year Ended December 31, 2018
Revenues and other income	$	324.9	$	251.4	$	86.1	$	-		$	662.4
Net income (loss)		193.0		148.8		36.1		(5.6	)		372.3
Net income (loss) attributable to Hess Midstream Partners LP		38.4		30.7		7.3		(5.6	)		70.8
Depreciation expense		63.3		43.9		15.8		-			123.0
Interest expense		-		-		-		1.3			1.3
Adjusted EBITDA		256.3		192.7		51.9		(4.3	)		496.6
Adjusted EBITDA attributable to Hess Midstream Partners LP		51.0		39.5		10.5		(4.3	)		96.7
Capital expenditures		250.4		10.0		4.3		-			264.7

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Year Ended December 31, 2017
Revenues and other income	$	271.6	$	227.3	$	66.7	$	0.2		$	565.8
Net income (loss)		149.9		123.8		14.4		(3.3	)		284.8
Net income (loss) attributable to Hess Midstream Partners LP		23.3		18.8		2.4		(3.3	)		41.2
Depreciation expense		54.4		43.6		15.1		-			113.1
Interest expense		-		-		-		1.4			1.4
Adjusted EBITDA		204.3		167.4		29.5		(1.9	)		399.3
Adjusted EBITDA attributable to Hess Midstream Partners LP		31.5		25.1		4.6		(1.9	)		59.3
Capital expenditures		72.7		15.9		24.6		-			113.2

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP Predecessor
(in millions)
For the Year Ended December 31, 2016
Revenues and other income	$	212.8	$	196.7	$	100.3	$	-		$	509.8
Net income (loss)		96.9		92.7		16.7		(1.4	)		204.9
Depreciation expense		39.9		44.0		15.8		-			99.7
Interest expense		-		-		-		1.4			1.4
Adjusted EBITDA		136.8		136.7		32.5		-			306.0
Capital expenditures		208.3		35.4		21.2		-			264.9

Total Assets for Reportable Segments

Total assets for reportable segments are as follows:


	December 31, 2018		December 31, 2017
(in millions)
Gathering	$	1,467.7	$	1,280.5
Processing and Storage⁽¹⁾		1,008.6		972.8
Terminaling and Export		320.2		330.8
Interest and Other		23.2		51.0
Total assets	$	2,819.7	$	2,635.1

⁽¹⁾Includes $67.3 million of investment in equity method investees.

Supplemental Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of Supplemental Quarterly Financial Information (Unaudited)

Supplemental quarterly financial information is as follows:

	2018
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
(in millions, except per unit amounts)
Revenues and other income	$	157.0	$	164.7	$	169.5	$	171.2
Income from operations	$	89.3	$	95.0	$	97.1	$	92.2
Net income	$	89.0	$	94.6	$	96.8	$	91.9
Net income attributable to Hess Midstream Partners LP	$	17.0	$	17.8	$	18.8	$	17.2
Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):
Common	$	0.30	$	0.32	$	0.34	$	0.31
Subordinated	$	0.30	$	0.32	$	0.34	$	0.31

	2017
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
(in millions, except per unit amounts)	Predecessor
Revenues and other income	$	130.3	$	138.3	$	146.7	$	150.5
Income from operations	$	63.1	$	68.6	$	76.9	$	77.6
Net income	$	63.1	$	68.1	$	76.5	$	77.1
Net income attributable to Hess Midstream Partners LP	*		$	11.4	$	15.0	$	14.8
Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):
Common	*		$	0.21	$	0.27	$	0.26
Subordinated	*		$	0.21	$	0.27	$	0.26

*Information is not applicable for the period prior to the Partnership’s IPO on April 10, 2017.

Description of Business - Additional Information (Detail) $ / shares in Units, $ in Millions			12 Months Ended
	Jan. 25, 2018 MMcf	Apr. 10, 2017 USD ($) $ / shares shares	Dec. 31, 2018 Segment	Dec. 31, 2017 USD ($)
Description Of Business [Line Items]
Initial public offering, common units \| shares		16,997,000
Percentage of ownership interest		2.00%	2.00%
Net proceeds from IPO		$ 365.5		$ 365.5
Underwriting discount and structuring fee		25.4
Cash distributed		$ 350.6
Cash distributed				$ 349.5
Number of operating segments \| Segment			3
LM4
Description Of Business [Line Items]
Percentage of ownership in joint venture	50.00%
Gas processing plant capacity \| MMcf	200
Hess T G P Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership interest	20.00%
Hess T G P Operations Limited Partnership \| Hess Infrastructure Partners LP
Description Of Business [Line Items]
Percentage of ownership interest	80.00%
Hess T G P Operations Limited Partnership \| LM4
Description Of Business [Line Items]
Percentage of ownership in joint venture	50.00%
Targa Resources Corp. \| LM4
Description Of Business [Line Items]
Percentage of ownership in joint venture	50.00%
Over-Allotment Option
Description Of Business [Line Items]
Initial public offering, common units \| shares		2,217,000
Percentage of ownership interest		30.50%
Shares Issued, Price Per Share \| $ / shares		$ 23.00
Hess Infrastructure Partners LP \| IPO \| Gathering Opco
Description Of Business [Line Items]
Percentage of ownership interest		20.00%
Hess Infrastructure Partners LP \| IPO \| Hess T G P Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership interest		20.00%
Hess Infrastructure Partners LP \| IPO \| Hess North Dakota Export Logistics Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership interest		20.00%
Hess Infrastructure Partners LP \| IPO \| Hess Mentor Storage Holdings Limited Liability Company
Description Of Business [Line Items]
Percentage of ownership interest		100.00%
Hess Corporation
Description Of Business [Line Items]
Percentage of ownership in joint venture			50.00%
GIP II Blue Holding Partnership, LP
Description Of Business [Line Items]
Percentage of ownership in joint venture			50.00%
Hess Infrastructure Partners LP
Description Of Business [Line Items]
Percentage of ownership interest		67.50%
Hess Infrastructure Partners LP \| Common Units
Description Of Business [Line Items]
Common and subordinated units issued \| shares		10,282,654
Hess Infrastructure Partners LP \| Subordinated Units
Description Of Business [Line Items]
Common and subordinated units issued \| shares		27,279,654
Hess and GIP \| Hess Infrastructure Partners LP
Description Of Business [Line Items]
Cash distributed		$ 349.5

Related Party Transactions - Additional Information (Detail) - USD ($)		12 Months Ended
	Sep. 17, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Reimbursement revenue		$ 661,700,000	$ 565,600,000
Predecessor
Related Party Transaction [Line Items]
Reimbursement revenue				$ 509,800,000
Credit Concentration Risk \| Revenue
Related Party Transaction [Line Items]
Revenues attributable to fee based commercial agreements		100.00%	100.00%	100.00%
Hess
Related Party Transaction [Line Items]
Minimum volume shortfall fee payments earned		$ 47,500,000	$ 61,600,000
Hess \| Predecessor
Related Party Transaction [Line Items]
Minimum volume shortfall fee payments earned				$ 36,500,000
Hess \| Rail Transportation Costs
Related Party Transaction [Line Items]
Reimbursement revenue		16,800,000	17,000,000
Hess \| Rail Transportation Costs \| Predecessor
Related Party Transaction [Line Items]
Reimbursement revenue				31,700,000
Hess \| Electricity Fees
Related Party Transaction [Line Items]
Reimbursement revenue		$ 27,200,000	$ 24,900,000
Hess \| Electricity Fees \| Predecessor
Related Party Transaction [Line Items]
Reimbursement revenue				$ 24,100,000
Hess \| Credit Concentration Risk \| Revenue
Related Party Transaction [Line Items]
Revenues attributable to fee based commercial agreements		100.00%	100.00%	100.00%
Hess \| Amended and Restated Commercial Agreement
Related Party Transaction [Line Items]
Initial term of agreement	10 years
Agreement description		Each of our commercial agreements with Hess has an initial 10year term (“Initial Term”) and we have the unilateral right to extend each commercial agreement for one additional 10year term (“Secondary Term”).
Number of rights to extend the term of agreement		one
Secondary term of agreement	10 years
Hess \| Amended and Restated Agreement for Certain Gas Gathering Sub-system
Related Party Transaction [Line Items]
Initial term of agreement	15 years
Agreement description		The amended and restated gas gathering agreement also extends the Initial Term of the gathering agreement with respect to a certain gathering sub-system by 5 years to provide for a 15-year Initial Term and decreases the Secondary Term for that gathering sub-system by 5 years to provide for a 5-year Secondary Term.
Secondary term of agreement	5 years
Initial term to extend by period	5 years
Secondary term to reduce by period	5 years
Hess Infrastructure Partners LP
Related Party Transaction [Line Items]
Contribution agreement expiration period		April 2019
Hess Infrastructure Partners LP \| Maintenance Capital Projects
Related Party Transaction [Line Items]
Reimbursement of maintenance expenses		$ 3,500,000	$ 16,900,000	$ 0

Property, Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 3,390.7	$ 3,124.5
Accumulated depreciation	(726.6)	(604.0)
Property, plant and equipment, net	2,664.1	2,520.5
Logistics Facilities and Railcars
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	385.8	371.1
Storage Facilities
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	19.5	19.5
Other
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	10.7	9.2
Construction-In-Progress
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 157.3	69.5
Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	12 years
Minimum \| Logistics Facilities and Railcars
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	20 years
Minimum \| Storage Facilities
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	20 years
Minimum \| Other
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	20 years
Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	35 years
Maximum \| Logistics Facilities and Railcars
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	25 years
Maximum \| Storage Facilities
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	25 years
Maximum \| Other
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	25 years
Gathering Assets \| Pipelines
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	22 years
Total property, plant and equipment, at cost	$ 1,003.9	890.8
Gathering Assets \| Compressors, Pumping Stations and Terminals
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 557.5	535.5
Gathering Assets \| Minimum \| Compressors, Pumping Stations and Terminals
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	22 years
Gathering Assets \| Maximum \| Compressors, Pumping Stations and Terminals
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	25 years
Gas Plant Assets \| Pipelines, Pipes and Valves
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 460.0	460.0
Gas Plant Assets \| Equipment
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 428.2	428.2
Gas Plant Assets \| Buildings
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	35 years
Total property, plant and equipment, at cost	$ 182.3	182.3
Gas Plant Assets \| Processing and Fractionation Facilities
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	25 years
Total property, plant and equipment, at cost	$ 185.5	$ 158.4
Gas Plant Assets \| Minimum \| Pipelines, Pipes and Valves
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	22 years
Gas Plant Assets \| Minimum \| Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	12 years
Gas Plant Assets \| Maximum \| Pipelines, Pipes and Valves
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	25 years
Gas Plant Assets \| Maximum \| Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, Estimated useful life	30 years

Unit-Based Compensation - Schedule of Unit-based Award Activity (Detail) - Phantom Units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding and unvested units at December 31, 2017, Number of Units	44,127
Granted, Number of Units	90,594
Forfeited, Number of Units	(3,107)
Vested, Number of Units	(17,377)
Outstanding and unvested units at December 31, 2018, Number of Units	114,237	44,127
Outstanding and unvested units at December 31, 2017, Weighted Average Award Date Fair Value	$ 22.85
Granted, Weighted Average Award Date Fair Value	20.51
Forfeited, Weighted Average Award Date Fair Value	21.73
Vested, Weighted Average Award Date Fair Value	22.63
Outstanding and unvested units at December 31, 2018, Weighed Average Award Date Fair Value	$ 21.06	$ 22.85
Fair value of units granted	$ 1.9	$ 1.0
Fair value of units vested	$ 0.4

Net Income per Limited Partner Unit - Partnership's Calculation of Net Income per Limited Partner Unit (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Limited Partners Capital Account [Line Items]
Net income	$ 91.9	$ 96.8	$ 94.6	$ 89.0	$ 77.1	$ 76.5	$ 68.1		$ 372.3	$ 284.8
Less: Net income attributable to noncontrolling interest									301.5	175.4
Net income attributable to Hess Midstream Partners LP	$ 17.2	$ 18.8	$ 17.8	$ 17.0	$ 14.8	$ 15.0	$ 11.4		70.8	41.2
Less: General partner interest in net income attributable to Hess Midstream Partners LP									1.7	0.8
Limited partners' interest in net income attributable to Hess Midstream Partners LP									69.1	40.4
Predecessor
Limited Partners Capital Account [Line Items]
Net income								$ 63.1		68.2	$ 204.9
Common Units
Limited Partners Capital Account [Line Items]
Common unitholders' interest in net income attributable to Hess Midstream Partners LP									$ 34.6	$ 20.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Basic and diluted	$ 0.31	$ 0.34	$ 0.32	$ 0.30	$ 0.26	$ 0.27	$ 0.21		$ 1.27	$ 0.75
Weighted average limited partner units outstanding, Basic:
Units outstanding, Basic									27.3	26.9
Weighted average limited partner units outstanding, Diluted:
Units outstanding, Diluted									27.4	26.9
Subordinated Units
Limited Partners Capital Account [Line Items]
Common unitholders' interest in net income attributable to Hess Midstream Partners LP									$ 34.5	$ 20.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Basic and diluted	$ 0.31	$ 0.34	$ 0.32	$ 0.30	$ 0.26	$ 0.27	$ 0.21		$ 1.27	$ 0.75
Weighted average limited partner units outstanding, Basic:
Units outstanding, Basic									27.3	26.9
Weighted average limited partner units outstanding, Diluted:
Units outstanding, Diluted									27.3	26.9

Segments - Financial Data for Each Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues and other income	$ 171.2	$ 169.5	$ 164.7	$ 157.0	$ 150.5	$ 146.7	$ 138.3		$ 662.4	$ 565.8
Net income (loss)	91.9	96.8	94.6	89.0	77.1	76.5	68.1		372.3	284.8
Net income (loss) attributable to Hess Midstream Partners LP	$ 17.2	$ 18.8	$ 17.8	$ 17.0	$ 14.8	$ 15.0	$ 11.4		70.8	41.2
Depreciation expense									123.0	113.1
Interest expense, net									1.3	1.4
Adjusted EBITDA									496.6	399.3
Adjusted EBITDA attributable to Hess Midstream Partners LP									96.7	59.3
Capital expenditures									264.7	113.2
Predecessor
Segment Reporting Information [Line Items]
Revenues and other income								$ 130.3			$ 509.8
Net income (loss)								$ 63.1		68.2	204.9
Depreciation expense											99.7
Interest expense, net											1.4
Adjusted EBITDA											306.0
Capital expenditures											264.9
Interest and Other
Segment Reporting Information [Line Items]
Revenues and other income										0.2
Net income (loss)									(5.6)	(3.3)
Net income (loss) attributable to Hess Midstream Partners LP									(5.6)	(3.3)
Interest expense, net									1.3	1.4
Adjusted EBITDA									(4.3)	(1.9)
Adjusted EBITDA attributable to Hess Midstream Partners LP									(4.3)	(1.9)
Interest and Other \| Predecessor
Segment Reporting Information [Line Items]
Net income (loss)											(1.4)
Interest expense, net											1.4
Gathering Opco \| Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income									324.9	271.6
Net income (loss)									193.0	149.9
Net income (loss) attributable to Hess Midstream Partners LP									38.4	23.3
Depreciation expense									63.3	54.4
Adjusted EBITDA									256.3	204.3
Adjusted EBITDA attributable to Hess Midstream Partners LP									51.0	31.5
Capital expenditures									250.4	72.7
Gathering Opco \| Operating Segments \| Predecessor
Segment Reporting Information [Line Items]
Revenues and other income											212.8
Net income (loss)											96.9
Depreciation expense											39.9
Adjusted EBITDA											136.8
Capital expenditures											208.3
Processing and Storage \| Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income									251.4	227.3
Net income (loss)									148.8	123.8
Net income (loss) attributable to Hess Midstream Partners LP									30.7	18.8
Depreciation expense									43.9	43.6
Adjusted EBITDA									192.7	167.4
Adjusted EBITDA attributable to Hess Midstream Partners LP									39.5	25.1
Capital expenditures									10.0	15.9
Processing and Storage \| Operating Segments \| Predecessor
Segment Reporting Information [Line Items]
Revenues and other income											196.7
Net income (loss)											92.7
Depreciation expense											44.0
Adjusted EBITDA											136.7
Capital expenditures											35.4
Terminaling and Export \| Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income									86.1	66.7
Net income (loss)									36.1	14.4
Net income (loss) attributable to Hess Midstream Partners LP									7.3	2.4
Depreciation expense									15.8	15.1
Adjusted EBITDA									51.9	29.5
Adjusted EBITDA attributable to Hess Midstream Partners LP									10.5	4.6
Capital expenditures									$ 4.3	$ 24.6
Terminaling and Export \| Operating Segments \| Predecessor
Segment Reporting Information [Line Items]
Revenues and other income											100.3
Net income (loss)											16.7
Depreciation expense											15.8
Adjusted EBITDA											32.5
Capital expenditures											$ 21.2

Subsequent Events - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions

12 Months Ended

Feb. 26, 2019

Jan. 24, 2019

Dec. 31, 2018

Dec. 31, 2017

Subsequent Event [Line Items]

Quarterly cash distribution declared per common and subordinated unit

^[1]

$ 1.4061

$ 0.9028

Subsequent Event

Subsequent Event [Line Items]

Quarterly cash distribution declared date

Jan. 24, 2019

Quarterly cash distribution declared per common and subordinated unit

$ 0.3701

Distribution made to limited partner, increase in percentage than prior year quarter declared

15.00%

Distribution paid date

Feb. 13, 2019

Record Date

Feb. 04, 2019

Subsequent Event | Hess North Dakota Pipelines LLC | Crude Oil and Gas Gathering Assets | Summit Midstream Partners' Tioga Gathering System

Subsequent Event [Line Items]

Acquisition agreement entered date

Feb. 26, 2019

Cash consideration

$ 60

Potential contingent payments, subject to certain future performance metrics

$ 7

[1]	Represents cash distributions declared during the month following the end of each respective quarterly period. See Note 13, Subsequent Events.

Supplemental Quarterly Financial Information (Unaudited) - Schedule of Supplemental Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Line Items]
Revenues and other income	$ 171.2	$ 169.5	$ 164.7	$ 157.0	$ 150.5	$ 146.7	$ 138.3		$ 662.4	$ 565.8
Income from operations	92.2	97.1	95.0	89.3	77.6	76.9	68.6		373.6	286.2
Net income	91.9	96.8	94.6	89.0	77.1	76.5	68.1		372.3	284.8
Net income attributable to Hess Midstream Partners LP	$ 17.2	$ 18.8	$ 17.8	$ 17.0	$ 14.8	$ 15.0	$ 11.4		$ 70.8	41.2
Predecessor
Quarterly Financial Information [Line Items]
Revenues and other income								$ 130.3			$ 509.8
Income from operations								63.1			206.3
Net income								$ 63.1		$ 68.2	$ 204.9
Common Units
Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):
Net income attributable to Hess Midstream Partners per limited partner unit	$ 0.31	$ 0.34	$ 0.32	$ 0.30	$ 0.26	$ 0.27	$ 0.21		$ 1.27	$ 0.75
Subordinated Units
Net income attributable to Hess Midstream Partners LP per limited partner unit (basic and diluted):
Net income attributable to Hess Midstream Partners per limited partner unit	$ 0.31	$ 0.34	$ 0.32	$ 0.30	$ 0.26	$ 0.27	$ 0.21		$ 1.27	$ 0.75

Summary of Significant Accounting Policies and Basis of Presentation - Additional Information (Detail) - USD ($)		12 Months Ended
	Apr. 10, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Line Items]
Doubtful accounts written off		$ 0	$ 0
Allowance for doubtful accounts		0	0
Impairment of long-lived assets		0	0	$ 0
Cash contributed to acquire equity method investments		$ 67,300,000
Percentage of ownership interest	2.00%	2.00%
Minimum
Accounting Policies [Line Items]
Depreciation lives of assets		12 years
Maximum
Accounting Policies [Line Items]
Depreciation lives of assets		35 years
LM4
Accounting Policies [Line Items]
Cash contributed to acquire equity method investments		$ 67,300,000
Revolving Credit Facility \| Other Noncurrent Assets
Accounting Policies [Line Items]
Unamortized deferred financing costs		$ 2,200,000	$ 3,200,000
Predecessor \| Gathering Opco, HTGP Opco, Logistics Opco and Mentor Storage Terminal
Accounting Policies [Line Items]
Percentage of operations prior to IPO	100.00%
Cash				$ 0

Accrued Liabilities and Other Current Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities Current [Abstract]
Accrued capital expenditures	$ 51.9	$ 22.8
Other accruals	12.6	9.9
Total	$ 64.5	$ 32.7

Accrued Liabilities and Other Current Liabilities - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities Current [Abstract]
Other current liabilities	$ 6.8	$ 7.0

Debt and Interest Expense - Additional Information (Detail) - USD ($)		12 Months Ended
	Mar. 15, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Line of credit interest paid on credit facilities, including facility fees		$ 600,000
Predecessor
Debt Instrument [Line Items]
Line of credit interest paid on credit facilities, including facility fees			$ 600,000	$ 400,000
Senior Secured Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility - Term	4 years
Maximum borrowing capacity	$ 300,000,000
Percentage of facility fees accrued per annum and paid quarterly	0.275%
Debt covenant, leverage ratio		450.00%
Senior Secured Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate, applicable margin	1.275%

Distributions - Additional Information (Detail)	12 Months Ended
Distributions - Additional Information (Detail)	Dec. 31, 2018
Distributions Made To Members Or Limited Partners [Abstract]
Period of cash distribution to unitholders	45 days

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Dec. 31, 2018	Dec. 31, 2017
Common Unitholders - Public
Common and subordinated units issued	17,014,377	16,997,000
Common and subordinated units outstanding	17,014,377	16,997,000
Common Unitholders - Affiliate
Common and subordinated units issued	10,282,654	10,282,654
Common and subordinated units outstanding	10,282,654	10,282,654
Subordinated Unitholders - Affiliate
Common and subordinated units issued	27,279,654	27,279,654
Common and subordinated units outstanding	27,279,654	27,279,654

Distributions - Schedule of Distributions Declared and Paid (Parenthetical) (Detail)	3 Months Ended
	Jun. 30, 2017 $ / shares
Distributions Made To Members Or Limited Partners [Abstract]
Minimum quarterly distribution per unit	$ 0.3000

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Estimated remediation liabilities included in accrued liabilities	$ 600,000	$ 1,000,000
Estimated remediation liabilities included in other noncurrent liabilities	2,000,000	2,400,000
Accrued liabilities for legal contingencies	0	$ 0
Lease and purchase obligations, due in next fiscal year	200,000
Lease and purchase obligations, due thereafter	300,000
Unconditional purchase obligation, due in next fiscal year	12,700,000
Unconditional purchase obligation, due thereafter	$ 0

Segments - Additional Information (Detail)	12 Months Ended
Segments - Additional Information (Detail)	Dec. 31, 2018 Segment Railcar mi	Jan. 25, 2018
Segment Reporting Information [Line Items]
Number of reportable segments \| Segment	3
Number of crude oil rail cars	550
McKenzie County
Segment Reporting Information [Line Items]
Crude oil pipeline length \| mi	6
Minimum
Segment Reporting Information [Line Items]
Number of crude oil rail cars, operate as unit trains	100
Maximum
Segment Reporting Information [Line Items]
Number of crude oil rail cars, operate as unit trains	110
LM4
Segment Reporting Information [Line Items]
Percentage of ownership in joint venture		50.00%

Segments - Total Assets for Reportable Segments (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Cash contributed to acquire equity method investments	$ 67.3
Processing and Storage
Segment Reporting Information [Line Items]
Cash contributed to acquire equity method investments	$ 67.3