View Filing Data

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2019 shares
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	HESM
Entity Registrant Name	Hess Midstream Partners LP
Entity Central Index Key	0001619739
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity File Number	001-38050
Entity Tax Identification Number	36-4777695
Entity Address, Address Line One	1501 McKinney Street
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77010
City Area Code	713
Local Phone Number	496-4200
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Units
Security Exchange Name	NYSE
Entity Interactive Data Current	Yes
Common Units
Document And Entity Information [Line Items]
Entity Units Outstanding	27,345,309
Subordinated Units
Document And Entity Information [Line Items]
Entity Units Outstanding	27,279,654

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	$ 3.5	$ 20.3
Accounts receivable—affiliate:
From contracts with customers	68.2	62.2
Other receivables	0.1	0.8
Other current assets	7.4	2.8
Total current assets	79.2	86.1
Equity investments	100.8	67.3
Property, plant and equipment, net	2,823.1	2,664.1
Other noncurrent assets	2.2	2.2
Total assets	3,005.3	2,819.7
Liabilities
Accounts payable—trade	17.7	15.3
Accounts payable—affiliate	47.6	15.8
Accrued liabilities	54.5	64.5
Other current liabilities	6.6	6.8
Total current liabilities	126.4	102.4
Long-term debt	11.0
Other noncurrent liabilities	10.9	6.4
Total liabilities	148.3	108.8
Partners' capital
General partner	15.5	14.9
Total Hess Midstream Partners LP partners' capital	506.4	516.8
Noncontrolling interest	2,350.6	2,194.1
Total partners' capital	2,857.0	2,710.9
Total liabilities and partners' capital	3,005.3	2,819.7
Common Unitholders - Public
Partners' capital
Common and subordinated unitholders	354.2	357.1
Common Unitholders - Affiliate
Partners' capital
Common and subordinated unitholders	37.5	39.5
Subordinated Unitholders - Affiliate
Partners' capital
Common and subordinated unitholders	$ 99.2	$ 105.3

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Sep. 30, 2019	Dec. 31, 2018
Common Unitholders - Public
Common and subordinated units issued	17,062,655	17,014,377
Common and subordinated units outstanding	17,062,655	17,014,377
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

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Affiliate services	$ 195.4	$ 169.3	$ 542.1	$ 490.6
Type of Revenue [Extensible List]	hesm:AffiliateServicesMember	hesm:AffiliateServicesMember	hesm:AffiliateServicesMember	hesm:AffiliateServicesMember
Other income		$ 0.2	$ 0.3	$ 0.6
Total revenues	$ 195.4	169.5	542.4	491.2
Costs and expenses
Operating and maintenance expenses (exclusive of depreciation shown separately below)	56.5	39.4	142.0	111.1
Depreciation expense	34.5	30.6	101.1	90.8
General and administrative expenses	3.9	2.4	11.6	7.9
Total costs and expenses	94.9	72.4	254.7	209.8
Income from operations	100.5	97.1	287.7	281.4
Earnings from equity investments	0.5		0.5
Interest expense, net	0.6	0.3	1.6	1.0
Net income	100.4	96.8	286.6	280.4
Less: Net income attributable to noncontrolling interest	81.3	78.0	232.6	226.8
Net income attributable to Hess Midstream Partners LP	19.1	18.8	54.0	53.6
Less: General partner's interest in net income attributable to Hess Midstream Partners LP	1.3	0.5	3.1	1.2
Limited partners' interest in net income attributable to Hess Midstream Partners LP	$ 17.8	$ 18.3	$ 50.9	$ 52.4
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	$ 0.33	$ 0.34	$ 0.93	$ 0.96
Weighted average limited partner units outstanding, Basic:
Units outstanding, Basic	27.3	27.3	27.3	27.3
Weighted average limited partner units outstanding, Diluted:
Units outstanding, Diluted	27.5	27.4	27.5	27.4
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	$ 0.33	$ 0.34	$ 0.93	$ 0.96
Weighted average limited partner units outstanding, Basic:
Units outstanding, Basic	27.3	27.3	27.3	27.3
Weighted average limited partner units outstanding, Diluted:
Units outstanding, Diluted	27.3	27.3	27.3	27.3

CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL (UNAUDITED) - USD ($) $ in Millions	Total	Limited Partners Common Unitholders Public	Limited Partners Common Unitholders Affiliate	Limited Partners Subordinated Unitholders Affiliate	General Partner	Noncontrolling Interest
Balance, beginning of period at Dec. 31, 2017	$ 2,555.3	$ 357.7	$ 40.5	$ 107.8	$ 14.8	$ 2,034.5
Net income	89.0	5.2	3.2	8.3	0.3	72.0
Unit-based compensation	0.1	0.1
Distributions to unitholders	(17.5)	(5.4)	(3.3)	(8.8)
Distributions to general partner	(0.4)				(0.4)
Distributions to noncontrolling interest	(61.7)					(61.7)
Contributions from noncontrolling interest	20.6					20.6
Balance, end of period at Mar. 31, 2018	2,585.4	357.6	40.4	107.3	14.7	2,065.4
Balance, beginning of period at Dec. 31, 2017	2,555.3	357.7	40.5	107.8	14.8	2,034.5
Net income	280.4
Balance, end of period at Sep. 30, 2018	2,687.6	357.6	40.2	106.6	14.9	2,168.3
Balance, beginning of period at Mar. 31, 2018	2,585.4	357.6	40.4	107.3	14.7	2,065.4
Net income	94.6	5.4	3.3	8.7	0.4	76.8
Unit-based compensation	0.3	0.3
Distributions to unitholders	(18.2)	(5.7)	(3.4)	(9.1)
Distributions to general partner	(0.4)				(0.4)
Distributions to noncontrolling interest	(41.5)					(41.5)
Contributions from noncontrolling interest	14.6					14.6
Balance, end of period at Jun. 30, 2018	2,634.8	357.6	40.3	106.9	14.7	2,115.3
Net income	96.8	5.7	3.4	9.2	0.5	78.0
Unit-based compensation	0.3	0.3
Distributions to unitholders	(19.0)	(6.0)	(3.5)	(9.5)
Distributions to general partner	(0.3)				(0.3)
Distributions to noncontrolling interest	(46.0)					(46.0)
Contributions from noncontrolling interest	21.0					21.0
Balance, end of period at Sep. 30, 2018	2,687.6	357.6	40.2	106.6	14.9	2,168.3
Balance, beginning of period at Dec. 31, 2018	2,710.9	357.1	39.5	105.3	14.9	2,194.1
Net income	95.3	5.3	3.4	8.6	0.8	77.2
Unit-based compensation	0.3	0.3
Distributions to unitholders	(20.2)	(6.3)	(3.8)	(10.1)
Distributions to general partner	(0.6)				(0.6)
Distributions to noncontrolling interest	(57.1)					(57.1)
Contributions from noncontrolling interest	55.5					55.5
Balance, end of period at Mar. 31, 2019	2,784.1	356.4	39.1	103.8	15.1	2,269.7
Balance, beginning of period at Dec. 31, 2018	2,710.9	357.1	39.5	105.3	14.9	2,194.1
Net income	286.6
Balance, end of period at Sep. 30, 2019	2,857.0	354.2	37.5	99.2	15.5	2,350.6
Balance, beginning of period at Mar. 31, 2019	2,784.1	356.4	39.1	103.8	15.1	2,269.7
Net income	90.9	4.9	3.0	7.9	1.0	74.1
Unit-based compensation	0.3	0.3
Distributions to unitholders	(21.0)	(6.5)	(4.0)	(10.5)
Distributions to general partner	(0.8)				(0.8)
Distributions to noncontrolling interest	(49.0)					(49.0)
Contributions from noncontrolling interest	12.8					12.8
Balance, end of period at Jun. 30, 2019	2,817.3	355.1	38.1	101.2	15.3	2,307.6
Net income	100.4	5.5	3.4	8.9	1.3	81.3
Unit-based compensation	0.5	0.5
Distributions to unitholders	(21.8)	(6.9)	(4.0)	(10.9)
Distributions to general partner	(1.1)				(1.1)
Distributions to noncontrolling interest	(46.3)					(46.3)
Contributions from noncontrolling interest	8.0					8.0
Balance, end of period at Sep. 30, 2019	$ 2,857.0	$ 354.2	$ 37.5	$ 99.2	$ 15.5	$ 2,350.6

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL (UNAUDITED) (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Statement Of Partners Capital [Abstract]
Distributions to unitholders - per unit	$ 0.3970	$ 0.3833	$ 0.3701	$ 0.3452	$ 0.3333	$ 0.3218

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net income	$ 286.6	$ 280.4
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense	101.1	90.8
Amortization of deferred financing costs	0.9	0.8
Unit-based compensation expense	1.1	0.7
Earnings from equity investments	(0.5)
Changes in assets and liabilities:
Accounts receivable – affiliate	(5.2)	(5.7)
Other current and noncurrent assets	(5.0)	(0.7)
Accounts payable – trade	2.2	0.6
Accounts payable – affiliate	4.3	0.8
Accrued liabilities	9.2	2.5
Other current and noncurrent liabilities	(2.5)	(2.8)
Net cash provided by (used in) operating activities	392.2	367.4
Cash flows from investing activities
Acquisitions from third parties, net of cash acquired	(61.0)
Payments for equity investments	(33.0)	(67.3)
Additions to property, plant and equipment	(184.4)	(163.9)
Net cash provided by (used in) investing activities	(278.4)	(231.2)
Cash flows from financing activities
Proceeds from (repayments of) bank borrowings - revolver	11.0
Distributions to unitholders	(63.0)	(54.7)
Distributions to general partner	(2.5)	(1.1)
Distributions to noncontrolling interest	(152.4)	(149.2)
Contributions from noncontrolling interest	76.3	56.2
Net cash provided by (used in) financing activities	(130.6)	(148.8)
Increase (decrease) in cash and cash equivalents	(16.8)	(12.6)
Cash and cash equivalents, beginning of period	20.3	47.2
Cash and cash equivalents, end of period	$ 3.5	$ 34.6

Description of Business

9 Months Ended

Sep. 30, 2019

Description Of Business [Abstract]

Description of Business

Note 1. Description of Business

Hess Midstream Partners LP (the “Partnership” or “HESM”) is a fee‑based, growth-oriented traditional master limited partnership formed by Hess Infrastructure Partners LP (“Hess Infrastructure Partners” or “HIP”), a midstream joint venture with a 50% ownership interest held by affiliates of Hess Corporation (collectively “Hess”) and a 50% ownership interest held by GIP II Blue Holding Partnership LP (“GIP”), to own, operate, develop and acquire a diverse set of midstream assets to provide services to Hess and third‑party customers.

Our assets include a 20% controlling economic interest in each of (i) Hess North Dakota Pipelines Operations LP (“Gathering Opco”), which owns crude oil and natural gas gathering pipelines and compressor stations in North Dakota, (ii) Hess TGP Operations LP (“HTGP Opco”) which owns the Tioga Gas Plant (“TGP”), a natural gas processing and fractionation plant, including a residue gas pipeline in North Dakota, and (iii) Hess North Dakota Export Logistics Operations LP (“Logistics Opco”), which owns a crude oil and natural gas liquids (“NGL”) rail loading facility, crude oil rail cars and a crude oil pipeline and truck receipt terminal in North Dakota, and a 100% ownership interest in Hess Mentor Storage Holdings LLC (“Mentor Storage Terminal”), which owns a propane storage cavern and related rail and truck loading and unloading and storage terminal in Minnesota (collectively, the “Joint Interest Assets”). Hess Infrastructure Partners owns the remaining 80% economic interest in the Joint Interest Assets.

On January 25, 2018, we entered into a 50/50 joint venture with Targa Resources Corp. (“Targa”) to construct a new 200 million standard cubic feet per day gas processing plant called Little Missouri 4 (“LM4”). Our 50% interest in the joint venture is held through HTGP Opco, in which we own a 20% controlling economic interest and Hess Infrastructure Partners owns the remaining 80% economic interest. LM4 was placed into service in the third quarter of 2019. Targa is the operator of the plant.

On March 22, 2019, Hess North Dakota Pipelines LLC, a subsidiary of Gathering Opco, acquired the crude oil and gas gathering assets of Summit Midstream Partners, LP’s Tioga Gathering System. See Note 3, Acquisitions.

On October 4, 2019, we announced a proposed transaction, including acquisition of HIP, incentive distribution rights simplification and conversion to an “Up-C” corporate structure. See Note 14, Subsequent Events.

The terms “we,” “our” and “us” as used in this report refer to the Partnership, unless the context suggests otherwise. These terms are used for convenience only and are not intended as a precise description of any separate legal entity within the Partnership. The term “parent” refers to Hess Infrastructure Partners.

Our assets and operations are organized into the following three reportable segments: (1) gathering, (2) processing and storage and (3) terminaling and export (see Note 13, Segments).

Basis of Presentation

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Basis of Presentation

Note 2. Basis of Presentation

Presentation. The consolidated financial statements included in this report reflect all normal and recurring adjustments which, in the opinion of management, are necessary for a fair presentation of our consolidated financial position at September 30, 2019 and December 31, 2018, the consolidated results of operations for the three and nine months ended September 30, 2019 and 2018, and consolidated cash flows for the nine months ended September 30, 2019 and 2018. The unaudited results of operations for the interim periods reported are not necessarily indicative of results to be expected for the full year.

The consolidated financial statements were prepared in accordance with the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain notes or other financial information that are normally required by U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted from these interim consolidated financial statements. These financial statements, therefore, should be read in conjunction with the financial statements and related notes included in the Partnership’s annual report on Form 10‑K for the year ended December 31, 2018.

Consolidation. We consolidate the activities of Gathering Opco, HTGP Opco and Logistics Opco, which qualify as variable interest entities (“VIE”) under U.S. GAAP. 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 Joint Interest Assets and have a right to receive benefits and an obligation to absorb losses that could potentially be significant. All financial statement activities associated with VIEs are captured within gathering, processing and storage, and terminaling and export segments (see Note 13, Segments). We reflect a noncontrolling interest representing the retained limited partner interest owned by Hess Infrastructure Partners in the Joint Interest Assets in the consolidated financial statements of the Partnership. All intercompany transactions and balances within the Partnership have been eliminated.

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. Through September 30, 2019, we have contributed $100.3 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.

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 during the periods presented in this report.

Summary of Significant Accounting Policies

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2016-02, Leases, as a new Accounting Standards Codification (“ASC”) Topic, ASC 842. We adopted ASC 842 on January 1, 2019 using the modified retrospective method. Accordingly, comparative financial statements for periods prior to the adoption date of ASC 842 were not 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. As a result, no cumulative effect adjustment to Partners’ capital was recognized.

Leases. We determine if an arrangement is a lease at inception. Operating lease right-of-use assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The operating lease right-of-use asset includes any initial direct costs and excludes lease incentives received. The lease term used in measurement of our lease obligations may include periods covered by an option to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Partnership has elected not to recognize lease assets and lease liabilities for leases with a term of 12 months or less for all classes of underlying assets. Our lease agreements may include lease and non-lease components, which are generally accounted for separately.

As of September 30, 2019, we had $0.8 million of operating lease right-of-use assets included within other noncurrent assets on our consolidated balance sheet. Operating lease liabilities were $0.2 million and $0.6 million included within other current liabilities and other noncurrent liabilities, respectively, on our consolidated balance sheet. As of September 30, 2019, we did not have any finance leases.

Acquisitions

9 Months Ended

Sep. 30, 2019

Business Combinations [Abstract]

Acquisitions

Note 3. Acquisitions

On March 22, 2019, Hess North Dakota Pipelines LLC, a subsidiary of Gathering Opco, acquired 100% of the membership interests of Tioga Hydrocarbon Gathering Company LLC from Summit Midstream Partners, LP (the “Tioga System Acquisition”). This transaction was accounted for as an asset acquisition. The Tioga System, located in Williams County in western North Dakota, is complementary to the Partnership’s infrastructure, and is currently delivering volumes into the Partnership’s gathering system.

Hess North Dakota Pipelines LLC paid $61.0 million in cash at closing, net of cash acquired, and recognized a contingent liability for additional potential payments of $6.8 million in future periods subject to certain performance metrics. The purchase price was funded pro rata by the Partnership and Hess Infrastructure Partners, as indirect owners of Hess North Dakota Pipelines LLC.

Related Party Transactions

9 Months Ended

Sep. 30, 2019

Related Party Transactions

Note 4. Related Party Transactions

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. We elected the practical expedient to recognize revenue in the amount to which we have a right to invoice as permitted under ASC 606, Revenue from Contracts with Customers. 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.

In September 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 pays us a combined processing fee per Mcf of natural gas, or Mcf equivalent of NGLs, as applicable, for aggregate volumes processed (or to be processed) at TGP and LM4. 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, incorporates 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 three and nine months ended September 30, 2019 and 2018, 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. We retain control of our assets and the flow of volumes based on available capacity within our integrated gathering, processing and terminaling systems. 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 three and nine months ended September 30, 2019, we earned $3.0 million and $6.5 million, respectively, of minimum volume shortfall fee payments, compared with $11.5 million and $40.9 million for the three and nine months ended September 30, 2018, respectively. In addition, during the three and nine months ended September 30, 2019, we recognized, as part of affiliate revenues, $12.0 million and $24.1million, respectively, of reimbursements from Hess related to third‑party rail transportation costs, compared with $4.5 million and $12.1 million for the three and nine months ended September 30, 2018, respectively. Finally, during the three and nine months ended September 30, 2019, we recognized, as part of affiliate revenues, $8.3 million and $23.2 million, respectively, of reimbursements from Hess related to electricity fees, compared with $6.7 million and $20.1 million for the three and nine months ended September 30, 2018, respectively. The related third-party transportation costs and electricity fees were included in Operating and maintenance expenses in the accompanying unaudited consolidated statements of operations.

See Note 13, 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.

Omnibus and Employee Secondment Agreements

Under our omnibus and employee secondment agreements, Hess provides substantial operational and administrative services to us in support of our assets and operations. For the three and nine months ended September 30, 2019 and 2018, we had the following charges from Hess. 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.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
(in millions)
Operating and maintenance expenses	$	12.4	$	11.7	$	33.8	$	34.6
General and administrative expenses		2.9		1.7		8.2		4.9
Total	$	15.3	$	13.4	$	42.0	$	39.5

LM4 Agreements

Separately from our commercial agreements with Hess, effective January 24, 2018, we entered into a gas processing agreement with LM4 under which we deliver natural gas to LM4, and LM4 processes and redelivers certain volumes of residue gas and NGLs resulting from such processing services. The agreement has a 16-year initial term, after which it is automatically renewed for subsequent one-year terms unless terminated by either party. Under this agreement, we pay a processing fee per Mcf of natural gas and reimburse LM4 for our proportionate share of electricity costs. We are entitled to 50% of the available processing capacity of the LM4 gas processing plant. Should Targa not use all of the remaining processing capacity at the plant on any day, such unutilized portion of the available capacity will be available for our use. Regardless of the actual portion of the plant available capacity utilized by each joint venture member during a given period, under the LM4 amended and restated limited liability company agreement, profits and losses of the LM4 joint venture are allocated 50/50 between Targa and us. LM4 was placed in service in the third quarter of 2019.

During the three months ended September 30, 2019, we incurred $0.9 million of expenses under the LM4 gas processing agreement, which are included in Operating and maintenance expenses in the accompanying consolidated statements of operations. In addition, during the three months ended September 30, 2019, we recognized $0.5 million of earnings from equity investments, as presented in our accompanying consolidated statements of operations.

Contribution Agreement

Under our contribution, conveyance and assumption agreement, Hess Infrastructure Partners agreed to bear the cost of certain maintenance capital projects associated with the Joint Interest Assets. During the nine months ended September 30, 2019, Hess Infrastructure Partners contributed $0.4 million to us related to the reimbursement for those maintenance capital projects (2018: $2.4 million). This provision of the agreement expired in April 2019, the second anniversary of the Partnership’s IPO.

Property, Plant and Equipment

9 Months Ended

Sep. 30, 2019

Property Plant And Equipment [Abstract]

Property, Plant and Equipment

Note 5. Property, Plant and Equipment

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

	Estimated useful lives	September 30, 2019			December 31, 2018
(in millions, except for number of years)
Gathering assets
Pipelines	22 years	$	1,165.3		$	1,003.9
Compressors, pumping stations and terminals	22 to 25 years		654.3			557.5
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		188.2			185.5
Logistics facilities and railcars	20 to 25 years		385.5			385.8
Storage facilities	20 to 25 years		19.5			19.5
Other	20 to 25 years		10.7			10.7
Construction-in-progress	N/A		156.6			157.3
Total property, plant and equipment, at cost			3,650.6			3,390.7
Accumulated depreciation			(827.5	)		(726.6	)
Property, plant and equipment, net		$	2,823.1		$	2,664.1

Accrued Liabilities

9 Months Ended

Sep. 30, 2019

Accrued Liabilities Current [Abstract]

Accrued Liabilities

Note 6. Accrued Liabilities

Accrued liabilities are as follows:

	September 30, 2019		December 31, 2018
(in millions)
Accrued capital expenditures	$	32.7	$	51.9
Other accruals		21.8		12.6
Total	$	54.5	$	64.5

Debt and Interest Expense

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Debt and Interest Expense

Note 7. Debt and Interest Expense

Revolving Credit Facility

On March 15, 2017, we entered into a four‑year, $300.0 million senior secured revolving credit facility that became available to us upon the closing of the IPO on April 10, 2017. Borrowings on the credit facility generally bear interest at the London Interbank Offered Rate (“LIBOR”) plus an applicable margin of 1.275%. The interest rate is subject to adjustment based on the Partnership’s leverage ratio, which is calculated as total debt to EBITDA (as defined in the credit agreement). Facility fees accrue at 0.275% per annum and are paid quarterly. If the Partnership obtains credit ratings, pricing levels will be based on our credit ratings in effect from time to time. The Partnership is subject to customary covenants in the credit agreement, including a financial covenant that generally requires a leverage ratio of no more than 4.5 to 1.0 for the prior four fiscal quarters. As of September 30, 2019, we were in compliance with all covenants. The credit facility is secured by first priority perfected liens on substantially all directly owned assets of the Partnership and its wholly‑owned subsidiaries, including equity interests in subsidiaries, subject to certain customary exclusions. At September 30, 2019, borrowings of $11.0 million were drawn under this facility, for which the carrying value approximated fair value.

On October 4, 2019, we announced that, in conjunction with the proposed transaction, including acquisition of HIP, incentive distribution rights simplification and conversion into an “Up-C” corporate structure, HIP’s credit facilities will be retired, and HESM will assume approximately $800 million principal amount of HIP’s outstanding senior notes in exchange for the issuance of up to $800 million aggregate principal amount of newly issued HESM senior notes. In addition, HESM expects to incur additional borrowings of approximately $960 million, resulting in expected total debt of $1.77 billion at the close of the transaction. See Note 14, Subsequent Events.

Distributions

9 Months Ended

Sep. 30, 2019

Distributions Made To Members Or Limited Partners [Abstract]

Distributions

Note 8. Distributions

Our partnership agreement requires that, within 45 days after the end of each quarter, we distribute all of our available cash to unitholders of record on the applicable record date. The following table details the distributions declared and/or paid for the periods presented:

Period	Record Date	Distribution Date	Distribution per Common and Subordinated Unit
First Quarter 2018	May 4, 2018	May 14, 2018	$	0.3333
Second Quarter 2018	August 2, 2018	August 13, 2018	$	0.3452
Third Quarter 2018	November 5, 2018	November 13, 2018	$	0.3575
Fourth Quarter 2018	February 4, 2019	February 13, 2019	$	0.3701
First Quarter 2019	May 3, 2019	May 14, 2019	$	0.3833
Second Quarter 2019	August 5, 2019	August 13, 2019	$	0.3970
Third Quarter 2019⁽¹⁾	November 4, 2019	November 13, 2019	$	0.4112

⁽¹⁾ For more information, see Note 14, Subsequent Events.

Unit-Based Compensation

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Unit-Based Compensation

Note 9. 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. 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 nine months ended September 30, 2019 was as follows:

				Weighted Average
				Award Date
	Number of Units			Fair Value
Outstanding and unvested units at December 31, 2018		114,237		$	21.06
Granted		74,528			22.76
Forfeited		(290	)		23.00
Vested		(48,278	)		21.15
Outstanding and unvested units at September 30, 2019		140,197		$	21.93

As of September 30, 2019, $2.2 million of compensation cost related to 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

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Net Income per Limited Partner Unit

Note 10. 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 interest and incentive distribution rights.

The following table illustrates the Partnership’s calculation of net income per limited partner unit:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in millions, except per unit amounts)	2019		2018		2019		2018
Net income	$	100.4	$	96.8	$	286.6	$	280.4
Less: Net income attributable to noncontrolling interest		81.3		78.0		232.6		226.8
Net income attributable to Hess Midstream Partners LP		19.1		18.8		54.0		53.6
Less: General partner's interest in net income attributable to Hess Midstream Partners LP		1.3		0.5		3.1		1.2
Limited partners' interest in net income attributable to Hess Midstream Partners LP	$	17.8	$	18.3	$	50.9	$	52.4
Common unitholders' interest in net income attributable to Hess Midstream Partners LP	$	8.9	$	9.2	$	25.4	$	26.2
Subordinated unitholders' interest in net income attributable to Hess Midstream Partners LP	$	8.9	$	9.1	$	25.3	$	26.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Common (basic and diluted)	$	0.33	$	0.34	$	0.93	$	0.96
Subordinated (basic and diluted)	$	0.33	$	0.34	$	0.93	$	0.96
Weighted average number of limited partner units outstanding:
Basic:
Common		27.3		27.3		27.3		27.3
Subordinated		27.3		27.3		27.3		27.3
Diluted:
Common		27.5		27.4		27.5		27.4
Subordinated		27.3		27.3		27.3		27.3

Concentration of Credit Risk

9 Months Ended

Sep. 30, 2019

Risks And Uncertainties [Abstract]

Concentration of Credit Risk

Note 11. Concentration of Credit Risk

Hess represented approximately 100% of our total revenues and accounts receivable for the three and nine months ended September 30, 2019 and 2018.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 12. Commitments and Contingencies

Environmental Contingencies

The Partnership is subject to federal, state and local laws and regulations relating to the environment. As of September 30, 2019, our reserves for estimated remediation liabilities included in Accrued liabilities and Other noncurrent liabilities were $0.1 million and $2.8 million, respectively, compared with $0.6 million and $2.0 million, respectively, as of December 31, 2018.

Legal Proceedings

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.

As of September 30, 2019 and December 31, 2018, we did not have material accrued liabilities for legal contingencies. Based on currently available information, we believe it is remote that the outcome of known matters would have a material adverse impact on our financial condition, results of operations or cash flows.

Lease Obligations

From time to time, we enter into certain lease contracts in connection with ongoing business activities. As of September 30, 2019, we have future minimum lease payments of $0.2 million for the year ended December 31, 2019, and $0.6 million of minimum lease payments for the years thereafter.

Segments

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Segments

Note 13. Segments

Our operations are located in the United States and are organized into three reportable segments: (1) gathering, (2) processing and storage and (3) 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. Our CODM evaluates the segments’ operating performance based on multiple measures including Adjusted EBITDA, defined as net income (loss) before net interest expense, income tax (benefit), depreciation and amortization and our proportional share of depreciation of equity affiliates, as further adjusted to eliminate the impact of certain items that we do not consider indicative of our ongoing operating performance, such as other income and other non-cash, non‑recurring items, if applicable.

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 Three Months Ended September 30, 2019
Revenues and other income	$	86.4	$	74.0	$	35.0	$	-		$	195.4
Net income (loss)		44.9		42.8		14.3		(1.6	)		100.4
Net income (loss) attributable to Hess Midstream Partners LP		9.1		8.8		2.8		(1.6	)		19.1
Depreciation expense		19.3		11.2		4.0		-			34.5
Proportional share of equity affiliates' depreciation		-		0.5		-		-			0.5
Interest expense, net		-		-		-		0.6			0.6
Adjusted EBITDA		64.2		54.5		18.3		(1.0	)		136.0
Adjusted EBITDA attributable to Hess Midstream Partners LP		13.0		11.0		3.6		(1.0	)		26.6
Capital expenditures		85.9		15.0		0.4		-			101.3
	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Three Months Ended September 30, 2018
Revenues and other income	$	82.6	$	65.2	$	21.7	$	-		$	169.5
Net income (loss)		49.9		39.6		8.3		(1.0	)		96.8
Net income (loss) attributable to Hess Midstream Partners LP		10.1		8.1		1.6		(1.0	)		18.8
Depreciation expense		15.6		11.0		4.0		-			30.6
Interest expense, net		-		-		-		0.3			0.3
Adjusted EBITDA		65.5		50.6		12.3		(0.7	)		127.7
Adjusted EBITDA attributable to Hess Midstream Partners LP		13.2		10.3		2.4		(0.7	)		25.2
Capital expenditures		79.4		0.5		1.1		-			81.0

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Nine Months Ended September 30, 2019
Revenues and other income	$	245.6	$	208.0	$	88.8	$	-		$	542.4
Net income (loss)		128.6		124.2		38.8		(5.0	)		286.6
Net income (loss) attributable to Hess Midstream Partners LP		25.8		25.4		7.8		(5.0	)		54.0
Depreciation expense		55.6		33.5		12.0		-			101.1
Proportional share of equity affiliates' depreciation		-		0.5		-		-			0.5
Interest expense, net		-		-		-		1.6			1.6
Adjusted EBITDA		184.2		158.2		50.8		(3.4	)		389.8
Adjusted EBITDA attributable to Hess Midstream Partners LP		37.0		32.0		10.2		(3.4	)		75.8
Capital expenditures		236.7		23.7		0.1		-			260.5

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Nine Months Ended September 30, 2018
Revenues and other income	$	243.0	$	186.4	$	61.8	$	-		$	491.2
Net income (loss)		148.6		111.0		24.8		(4.0	)		280.4
Net income (loss) attributable to Hess Midstream Partners LP		29.8		22.8		5.0		(4.0	)		53.6
Depreciation expense		46.2		32.8		11.8		-			90.8
Interest expense, net		-		-		-		1.0			1.0
Adjusted EBITDA		194.8		143.8		36.6		(3.0	)		372.2
Adjusted EBITDA attributable to Hess Midstream Partners LP		38.9		29.4		7.4		(3.0	)		72.7
Capital expenditures		187.7		7.9		3.3		-			198.9

Total assets for the reportable segments are as follows:


	September 30, 2019		December 31, 2018
(in millions)
Gathering	$	1,649.4	$	1,467.7
Processing and Storage		1,037.9		1,008.6
Terminaling and Export		312.9		320.2
Interest and Other		5.1		23.2
Total assets	$	3,005.3	$	2,819.7

Subsequent Events

9 Months Ended

Sep. 30, 2019

Subsequent Events [Abstract]

Subsequent Events

Note 14. Subsequent Events

On October 24, 2019, the board of directors of our general partner declared a quarterly cash distribution of $0.4112 per common and subordinated unit for the quarter ended September 30, 2019, an increase of 15% compared with the quarter ended September 30, 2018. The distribution will be payable on November 13, 2019, to unitholders of record as of the close of business on November 4, 2019.

On October 4, 2019, HESM announced execution of a definitive agreement to acquire HIP, including HIP’s 80% interest in the Joint Interest Assets, and 100% interest in HIP’s water services business, and outstanding economic general partner interest and incentive distribution rights in HESM. As consideration for the contribution of Hess and GIP’s ownership interests in HIP, HESM will assume approximately $1.15 billion of HIP’s existing debt, will issue approximately 230 million limited partner units in HESM and pay a cash consideration of approximately $550 million to Hess and GIP, collectively.

Under the proposed transaction, HESM’s organizational structure will be converted into an “Up-C” structure in which incentive distribution right payments to sponsors are eliminated. Public unitholders will receive newly issued securities in a new public entity to be named “Hess Midstream LP” that will be taxed as a corporation for U.S. federal and state income tax purposes. In connection with the proposed transaction, HESM will own 100% of the underlying assets and be consolidated under Hess Midstream LP. HESM’s existing public unitholders will receive one class A share representing a limited partner interest in Hess Midstream LP for each HESM common unit they own. Hess and GIP’s ownership will be primarily through class B units of HESM that are exchangeable into class A shares of Hess Midstream LP on a one-for-one basis. Following the transaction, public shareholders will own 6% of the consolidated entity and Hess and GIP will each own 47% of the consolidated entity on an as-exchanged basis.

In conjunction with the proposed transaction, approximately $355 million in existing borrowings under HIP’s credit facilities will be retired and HESM will assume approximately $800 million principal amount of HIP’s outstanding senior notes in exchange for the issuance of up to $800 million aggregate principal amount of newly issued HESM senior notes. On October 4, 2019, HESM commenced the offer to exchange HIP notes for new notes to be issued by HESM and, on October 21, 2019, HESM announced that 99.32% of the aggregate principal amount of HIP’s notes have been validly tendered and not validly withdrawn pursuant to the exchange offer as of the early tender date. HESM expects to pay a consent payment of approximately $2.0 million on the settlement date. In addition, HESM expects to incur additional borrowings of approximately $960 million, resulting in expected total debt of $1.77 billion at the close of the transaction.

The proposed transaction has been unanimously approved by the HESM Board and by a conflicts committee of the HESM Board comprised of independent directors. The transaction is expected to close in the fourth quarter of 2019, subject to customary closing conditions and receipt of regulatory approvals. The transaction is expected to be treated for accounting purposes as a reorganization of entities under common control and recorded at the historical carrying values of the assets, liabilities and equity interests of the parties to the transaction. Furthermore, following the closing of the transaction, historical financial statements of HESM will be retrospectively recast to include the historical results of HIP.

Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2019
Accounting Policies [Abstract]
Presentation	Presentation. The consolidated financial statements included in this report reflect all normal and recurring adjustments which, in the opinion of management, are necessary for a fair presentation of our consolidated financial position at September 30, 2019 and December 31, 2018, the consolidated results of operations for the three and nine months ended September 30, 2019 and 2018, and consolidated cash flows for the nine months ended September 30, 2019 and 2018. The unaudited results of operations for the interim periods reported are not necessarily indicative of results to be expected for the full year. The consolidated financial statements were prepared in accordance with the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain notes or other financial information that are normally required by U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted from these interim consolidated financial statements. These financial statements, therefore, should be read in conjunction with the financial statements and related notes included in the Partnership’s annual report on Form 10‑K for the year ended December 31, 2018.
Consolidation	Consolidation. We consolidate the activities of Gathering Opco, HTGP Opco and Logistics Opco, which qualify as variable interest entities (“VIE”) under U.S. GAAP. 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 Joint Interest Assets and have a right to receive benefits and an obligation to absorb losses that could potentially be significant. All financial statement activities associated with VIEs are captured within gathering, processing and storage, and terminaling and export segments (see Note 13, Segments). We reflect a noncontrolling interest representing the retained limited partner interest owned by Hess Infrastructure Partners in the Joint Interest Assets in the consolidated financial statements of the Partnership. All intercompany transactions and balances within the Partnership have been eliminated.
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. Through September 30, 2019, we have contributed $100.3 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.
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 during the periods presented in this report.
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2016-02, Leases, as a new Accounting Standards Codification (“ASC”) Topic, ASC 842. We adopted ASC 842 on January 1, 2019 using the modified retrospective method. Accordingly, comparative financial statements for periods prior to the adoption date of ASC 842 were not 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. As a result, no cumulative effect adjustment to Partners’ capital was recognized.
Leases	Leases. We determine if an arrangement is a lease at inception. Operating lease right-of-use assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The operating lease right-of-use asset includes any initial direct costs and excludes lease incentives received. The lease term used in measurement of our lease obligations may include periods covered by an option to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Partnership has elected not to recognize lease assets and lease liabilities for leases with a term of 12 months or less for all classes of underlying assets. Our lease agreements may include lease and non-lease components, which are generally accounted for separately. As of September 30, 2019, we had $0.8 million of operating lease right-of-use assets included within other noncurrent assets on our consolidated balance sheet. Operating lease liabilities were $0.2 million and $0.6 million included within other current liabilities and other noncurrent liabilities, respectively, on our consolidated balance sheet. As of September 30, 2019, we did not have any finance leases.

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References

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-Section 05
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65884525&loc=d3e40913-109327

+ Details

Related Party Transactions (Tables)

9 Months Ended

Sep. 30, 2019

Summary of Classification of Charges between Operating and Maintenance Expenses and General and Administrative Expenses

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
(in millions)
Operating and maintenance expenses	$	12.4	$	11.7	$	33.8	$	34.6
General and administrative expenses		2.9		1.7		8.2		4.9
Total	$	15.3	$	13.4	$	42.0	$	39.5

Property, Plant and Equipment (Tables)

9 Months Ended

Sep. 30, 2019

Property Plant And Equipment [Abstract]

Components of Property, Plant and Equipment

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

	Estimated useful lives	September 30, 2019			December 31, 2018
(in millions, except for number of years)
Gathering assets
Pipelines	22 years	$	1,165.3		$	1,003.9
Compressors, pumping stations and terminals	22 to 25 years		654.3			557.5
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		188.2			185.5
Logistics facilities and railcars	20 to 25 years		385.5			385.8
Storage facilities	20 to 25 years		19.5			19.5
Other	20 to 25 years		10.7			10.7
Construction-in-progress	N/A		156.6			157.3
Total property, plant and equipment, at cost			3,650.6			3,390.7
Accumulated depreciation			(827.5	)		(726.6	)
Property, plant and equipment, net		$	2,823.1		$	2,664.1

Accrued Liabilities (Tables)

9 Months Ended

Sep. 30, 2019

Accrued Liabilities Current [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities are as follows:

	September 30, 2019		December 31, 2018
(in millions)
Accrued capital expenditures	$	32.7	$	51.9
Other accruals		21.8		12.6
Total	$	54.5	$	64.5

Distributions - (Tables)

9 Months Ended

Sep. 30, 2019

Distributions Made To Members Or Limited Partners [Abstract]

Schedule of Distributions Declared and Paid

The following table details the distributions declared and/or paid for the periods presented:

Period	Record Date	Distribution Date	Distribution per Common and Subordinated Unit
First Quarter 2018	May 4, 2018	May 14, 2018	$	0.3333
Second Quarter 2018	August 2, 2018	August 13, 2018	$	0.3452
Third Quarter 2018	November 5, 2018	November 13, 2018	$	0.3575
Fourth Quarter 2018	February 4, 2019	February 13, 2019	$	0.3701
First Quarter 2019	May 3, 2019	May 14, 2019	$	0.3833
Second Quarter 2019	August 5, 2019	August 13, 2019	$	0.3970
Third Quarter 2019⁽¹⁾	November 4, 2019	November 13, 2019	$	0.4112

⁽¹⁾ For more information, see Note 14, Subsequent Events.

Unit-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Unit-based Award Activity

Unit‑based award activity for the nine months ended September 30, 2019 was as follows:

				Weighted Average
				Award Date
	Number of Units			Fair Value
Outstanding and unvested units at December 31, 2018		114,237		$	21.06
Granted		74,528			22.76
Forfeited		(290	)		23.00
Vested		(48,278	)		21.15
Outstanding and unvested units at September 30, 2019		140,197		$	21.93

Net Income per Limited Partner Unit (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Schedule of Net Income per Limited Partner Unit

The following table illustrates the Partnership’s calculation of net income per limited partner unit:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in millions, except per unit amounts)	2019		2018		2019		2018
Net income	$	100.4	$	96.8	$	286.6	$	280.4
Less: Net income attributable to noncontrolling interest		81.3		78.0		232.6		226.8
Net income attributable to Hess Midstream Partners LP		19.1		18.8		54.0		53.6
Less: General partner's interest in net income attributable to Hess Midstream Partners LP		1.3		0.5		3.1		1.2
Limited partners' interest in net income attributable to Hess Midstream Partners LP	$	17.8	$	18.3	$	50.9	$	52.4
Common unitholders' interest in net income attributable to Hess Midstream Partners LP	$	8.9	$	9.2	$	25.4	$	26.2
Subordinated unitholders' interest in net income attributable to Hess Midstream Partners LP	$	8.9	$	9.1	$	25.3	$	26.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Common (basic and diluted)	$	0.33	$	0.34	$	0.93	$	0.96
Subordinated (basic and diluted)	$	0.33	$	0.34	$	0.93	$	0.96
Weighted average number of limited partner units outstanding:
Basic:
Common		27.3		27.3		27.3		27.3
Subordinated		27.3		27.3		27.3		27.3
Diluted:
Common		27.5		27.4		27.5		27.4
Subordinated		27.3		27.3		27.3		27.3

Segments (Tables)

9 Months Ended

Sep. 30, 2019

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 Three Months Ended September 30, 2019
Revenues and other income	$	86.4	$	74.0	$	35.0	$	-		$	195.4
Net income (loss)		44.9		42.8		14.3		(1.6	)		100.4
Net income (loss) attributable to Hess Midstream Partners LP		9.1		8.8		2.8		(1.6	)		19.1
Depreciation expense		19.3		11.2		4.0		-			34.5
Proportional share of equity affiliates' depreciation		-		0.5		-		-			0.5
Interest expense, net		-		-		-		0.6			0.6
Adjusted EBITDA		64.2		54.5		18.3		(1.0	)		136.0
Adjusted EBITDA attributable to Hess Midstream Partners LP		13.0		11.0		3.6		(1.0	)		26.6
Capital expenditures		85.9		15.0		0.4		-			101.3
	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Three Months Ended September 30, 2018
Revenues and other income	$	82.6	$	65.2	$	21.7	$	-		$	169.5
Net income (loss)		49.9		39.6		8.3		(1.0	)		96.8
Net income (loss) attributable to Hess Midstream Partners LP		10.1		8.1		1.6		(1.0	)		18.8
Depreciation expense		15.6		11.0		4.0		-			30.6
Interest expense, net		-		-		-		0.3			0.3
Adjusted EBITDA		65.5		50.6		12.3		(0.7	)		127.7
Adjusted EBITDA attributable to Hess Midstream Partners LP		13.2		10.3		2.4		(0.7	)		25.2
Capital expenditures		79.4		0.5		1.1		-			81.0

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Nine Months Ended September 30, 2019
Revenues and other income	$	245.6	$	208.0	$	88.8	$	-		$	542.4
Net income (loss)		128.6		124.2		38.8		(5.0	)		286.6
Net income (loss) attributable to Hess Midstream Partners LP		25.8		25.4		7.8		(5.0	)		54.0
Depreciation expense		55.6		33.5		12.0		-			101.1
Proportional share of equity affiliates' depreciation		-		0.5		-		-			0.5
Interest expense, net		-		-		-		1.6			1.6
Adjusted EBITDA		184.2		158.2		50.8		(3.4	)		389.8
Adjusted EBITDA attributable to Hess Midstream Partners LP		37.0		32.0		10.2		(3.4	)		75.8
Capital expenditures		236.7		23.7		0.1		-			260.5

	Gathering		Processing and Storage		Terminaling and Export		Interest and Other			Consolidated Hess Midstream Partners LP
(in millions)
For the Nine Months Ended September 30, 2018
Revenues and other income	$	243.0	$	186.4	$	61.8	$	-		$	491.2
Net income (loss)		148.6		111.0		24.8		(4.0	)		280.4
Net income (loss) attributable to Hess Midstream Partners LP		29.8		22.8		5.0		(4.0	)		53.6
Depreciation expense		46.2		32.8		11.8		-			90.8
Interest expense, net		-		-		-		1.0			1.0
Adjusted EBITDA		194.8		143.8		36.6		(3.0	)		372.2
Adjusted EBITDA attributable to Hess Midstream Partners LP		38.9		29.4		7.4		(3.0	)		72.7
Capital expenditures		187.7		7.9		3.3		-			198.9

Total Assets for Reportable Segments

Total assets for the reportable segments are as follows:


	September 30, 2019		December 31, 2018
(in millions)
Gathering	$	1,649.4	$	1,467.7
Processing and Storage		1,037.9		1,008.6
Terminaling and Export		312.9		320.2
Interest and Other		5.1		23.2
Total assets	$	3,005.3	$	2,819.7

Description of Business - Additional Information (Detail)		9 Months Ended
	Jan. 25, 2018 MMcf	Sep. 30, 2019 Segment	Jan. 24, 2018
Description Of Business [Line Items]
Number of operating segments \| Segment		3
LM4
Description Of Business [Line Items]
Percentage of ownership in joint venture	50.00%		50.00%
Gas processing plant capacity \| MMcf	200
LM4 \| Targa Resources Corp.
Description Of Business [Line Items]
Percentage of ownership in joint venture	50.00%		50.00%
LM4 \| Hess T G P Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership in joint venture	50.00%
Gathering Opco
Description Of Business [Line Items]
Percentage of ownership interest		20.00%
Hess T G P Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership interest	20.00%	20.00%
Hess North Dakota Export Logistics Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership interest		20.00%
Hess Mentor Storage Holdings Limited Liability Company
Description Of Business [Line Items]
Percentage of ownership interest		100.00%
Hess Infrastructure Partners LP
Description Of Business [Line Items]
Percentage of ownership interest		80.00%
Hess Infrastructure Partners LP \| Hess T G P Operations Limited Partnership
Description Of Business [Line Items]
Percentage of ownership interest	80.00%
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%

Basis of Presentation - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Line Items]
Cash contributed to acquire equity method investments	$ 33,000,000	$ 67,300,000
Operating lease right-of-use assets included within other noncurrent assets	$ 800,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Operating lease liabilities included within other current liabilities	$ 200,000
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Operating lease liabilities included within other noncurrent liabilities	$ 600,000
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Finance lease	$ 0
LM4
Accounting Policies [Line Items]
Cash contributed to acquire equity method investments	$ 100,300,000

Acquisitions - Additional Information (Details) - USD ($) $ in Millions		9 Months Ended
	Mar. 22, 2019	Sep. 30, 2019
Business Acquisition [Line Items]
Cash paid for business acquisition, net of cash acquired		$ 61.0
Hess North Dakota Pipelines LLC \| Tioga System Acquisition
Business Acquisition [Line Items]
Percentage of membership interest acquired	100.00%
Cash paid for business acquisition, net of cash acquired	$ 61.0
Potential contingent payments, subject to certain future performance metrics	$ 6.8

Related Party Transactions - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 24, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jan. 25, 2018
Related Party Transaction [Line Items]
Reimbursement revenue		$ 195,400,000	$ 169,300,000	$ 542,100,000	$ 490,600,000
Earnings from equity investments		500,000		$ 500,000
LM4
Related Party Transaction [Line Items]
Initial term of agreement	16 years
Agreement description				The agreement has a 16-year initial term, after which it is automatically renewed for subsequent one-year terms unless terminated by either party.
Percentage of gas processing plant capacity	50.00%
Percentage of ownership in joint venture	50.00%						50.00%
Expenses incurred under gas processing agreement		900,000
Earnings from equity investments		$ 500,000
Credit Concentration Risk \| Revenue
Related Party Transaction [Line Items]
Revenues attributable to fee based commercial agreements		100.00%	100.00%	100.00%	100.00%
Hess
Related Party Transaction [Line Items]
Minimum volume shortfall fee payments earned		$ 3,000,000	$ 11,500,000	$ 6,500,000	$ 40,900,000
Expenses incurred under gas processing agreement		12,400,000	11,700,000	33,800,000	34,600,000
Hess \| Rail Transportation Costs
Related Party Transaction [Line Items]
Reimbursement revenue		12,000,000	4,500,000	24,100,000	12,100,000
Hess \| Electricity Fees
Related Party Transaction [Line Items]
Reimbursement revenue		$ 8,300,000	$ 6,700,000	$ 23,200,000	$ 20,100,000
Hess \| Credit Concentration Risk \| Revenue
Related Party Transaction [Line Items]
Revenues attributable to fee based commercial agreements		100.00%	100.00%	100.00%	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 retains its 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
Targa Resources Corp. \| LM4
Related Party Transaction [Line Items]
Percentage of ownership in joint venture	50.00%						50.00%
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				$ 400,000	$ 2,400,000

Related Party Transactions - Summary of Classification of Charges between Operating and Maintenance Expenses and General and Administrative Expenses (Detail) - Hess - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Related Party Transaction [Line Items]
Operating and maintenance expenses	$ 12.4	$ 11.7	$ 33.8	$ 34.6
General and administrative expenses	2.9	1.7	8.2	4.9
Total	$ 15.3	$ 13.4	$ 42.0	$ 39.5

Property, Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 3,650.6	$ 3,390.7
Accumulated depreciation	(827.5)	(726.6)
Property, plant and equipment, net	2,823.1	2,664.1
Logistics Facilities and Railcars
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	385.5	385.8
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	10.7
Construction-In-Progress
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 156.6	157.3
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 \| 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	$ 1,165.3	1,003.9
Gathering Assets \| Compressors, Pumping Stations and Terminals
Property Plant And Equipment [Line Items]
Total property, plant and equipment, at cost	$ 654.3	557.5
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	$ 188.2	$ 185.5
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

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Accrued capital expenditures	$ 32.7	$ 51.9
Other accruals	21.8	12.6
Total	$ 54.5	$ 64.5

Debt and Interest Expense - Additional Information (Detail) - USD ($)			9 Months Ended
	Oct. 04, 2019	Mar. 15, 2017	Sep. 30, 2019
Debt Instrument [Line Items]
Borrowings facility			$ 11,000,000
Subsequent Event
Debt Instrument [Line Items]
Definitive agreement date	Oct. 04, 2019
Additional borrowings at close of transaction	$ 960,000,000
Total debt at close of transaction	1,770,000,000
Maximum \| Subsequent Event
Debt Instrument [Line Items]
Issuance of senior notes	800,000,000
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%
Borrowings facility			$ 11,000,000
Senior Secured Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate, applicable margin		1.275%
Notes \| Hess Infrastructure Partners LP \| Subsequent Event
Debt Instrument [Line Items]
Business combination, liabilities assumed, debt	$ 800,000,000

Distributions - Additional Information (Detail)	9 Months Ended
Distributions - Additional Information (Detail)	Sep. 30, 2019
Distributions Made To Members Or Limited Partners [Abstract]
Period of cash distribution to unitholders	45 days

Distributions - Schedule of Distributions Declared and Paid (Detail)

9 Months Ended

Sep. 30, 2019

$ / shares

First Quarter 2018

Distribution Made To Limited Partner [Line Items]

Record Date

May 04, 2018

Distribution Date

May 14, 2018

Distribution per Common and Subordinated Unit

$ 0.3333

Second Quarter 2018

Distribution Made To Limited Partner [Line Items]

Record Date

Aug. 02, 2018

Distribution Date

Aug. 13, 2018

Distribution per Common and Subordinated Unit

$ 0.3452

Third Quarter 2018

Distribution Made To Limited Partner [Line Items]

Record Date

Nov. 05, 2018

Distribution Date

Nov. 13, 2018

Distribution per Common and Subordinated Unit

$ 0.3575

Fourth Quarter 2018

Distribution Made To Limited Partner [Line Items]

Record Date

Feb. 04, 2019

Distribution Date

Feb. 13, 2019

Distribution per Common and Subordinated Unit

$ 0.3701

First Quarter 2019

Distribution Made To Limited Partner [Line Items]

Record Date

May 03, 2019

Distribution Date

May 14, 2019

Distribution per Common and Subordinated Unit

$ 0.3833

Second Quarter 2019

Distribution Made To Limited Partner [Line Items]

Record Date

Aug. 05, 2019

Distribution Date

Aug. 13, 2019

Distribution per Common and Subordinated Unit

$ 0.3970

Third Quarter 2019

Distribution Made To Limited Partner [Line Items]

Record Date

Nov. 04, 2019

^[1]

Distribution Date

Nov. 13, 2019

^[1]

Distribution per Common and Subordinated Unit

$ 0.4112

^[1]

[1]	For more information, see Note 14, Subsequent Events.

Unit-Based Compensation - Additional Information (Detail) - 2017 Long-Term Incentive Plan $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Available common units pursuant to vested awards \| shares	3,000,000
Cost related to unvested phantom units to be recognized \| $	$ 2.2
Cost related to unvested phantom units to be recognized, over an expected weighted-average period	1 year 10 months 24 days
Officers and Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Phantom units vesting period	3 years
Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Phantom units vesting period	1 year

Unit-Based Compensation - Schedule of Unit-based Award Activity (Detail) - Phantom Units	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding and unvested units at December 31, 2018, Number of Units \| shares	114,237
Granted, Number of Units \| shares	74,528
Forfeited, Number of Units \| shares	(290)
Vested, Number of Units \| shares	(48,278)
Outstanding and unvested units at September 30, 2019 , Number of Units \| shares	140,197
Outstanding and unvested units at December 31, 2018, Weighted Average Award Date Fair Value \| $ / shares	$ 21.06
Granted, Weighted Average Award Date Fair Value \| $ / shares	22.76
Forfeited, Weighted Average Award Date Fair Value \| $ / shares	23.00
Vested, Weighted Average Award Date Fair Value \| $ / shares	21.15
Outstanding and unvested units at September 30,2019 , Weighted Average Award Date Fair Value \| $ / shares	$ 21.93

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						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Limited Partners Capital Account [Line Items]
Net income	$ 100.4	$ 90.9	$ 95.3	$ 96.8	$ 94.6	$ 89.0	$ 286.6	$ 280.4
Less: Net income attributable to noncontrolling interest	81.3			78.0			232.6	226.8
Net income attributable to Hess Midstream Partners LP	19.1			18.8			54.0	53.6
Less: General partner's interest in net income attributable to Hess Midstream Partners LP	1.3			0.5			3.1	1.2
Limited partners' interest in net income attributable to Hess Midstream Partners LP	17.8			18.3			50.9	52.4
Common Units
Limited Partners Capital Account [Line Items]
Common unitholders' interest in net income attributable to Hess Midstream Partners LP	$ 8.9			$ 9.2			$ 25.4	$ 26.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Basic and diluted	$ 0.33			$ 0.34			$ 0.93	$ 0.96
Weighted average limited partner units outstanding, Basic:
Units outstanding, Basic	27.3			27.3			27.3	27.3
Weighted average limited partner units outstanding, Diluted:
Units outstanding, Diluted	27.5			27.4			27.5	27.4
Subordinated Units
Limited Partners Capital Account [Line Items]
Common unitholders' interest in net income attributable to Hess Midstream Partners LP	$ 8.9			$ 9.1			$ 25.3	$ 26.2
Net income attributable to Hess Midstream Partners LP per limited partner unit:
Basic and diluted	$ 0.33			$ 0.34			$ 0.93	$ 0.96
Weighted average limited partner units outstanding, Basic:
Units outstanding, Basic	27.3			27.3			27.3	27.3
Weighted average limited partner units outstanding, Diluted:
Units outstanding, Diluted	27.3			27.3			27.3	27.3

Concentration of Credit Risk - Additional Information (Detail) - Credit Concentration Risk	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Estimated remediation liabilities included in accrued liabilities	$ 100,000	$ 600,000
Estimated remediation liabilities included in other noncurrent liabilities	2,800,000	2,000,000
Accrued liabilities for legal contingencies	0	$ 0
Lease obligations, due in December 31, 2019	200,000
Lease obligations, due thereafter	$ 600,000

Segments - Additional Information (Detail)	9 Months Ended
Segments - Additional Information (Detail)	Sep. 30, 2019 Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segments - Financial Data for Each Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues and other income	$ 195.4			$ 169.5			$ 542.4	$ 491.2
Net income (loss)	100.4	$ 90.9	$ 95.3	96.8	$ 94.6	$ 89.0	286.6	280.4
Net income (loss) attributable to Hess Midstream Partners LP	19.1			18.8			54.0	53.6
Depreciation expense	34.5			30.6			101.1	90.8
Proportional share of equity affiliates' depreciation	0.5						0.5
Interest expense, net	0.6			0.3			1.6	1.0
Adjusted EBITDA	136.0			127.7			389.8	372.2
Adjusted EBITDA attributable to Hess Midstream Partners LP	26.6			25.2			75.8	72.7
Capital expenditures	101.3			81.0			260.5	198.9
Interest and Other
Segment Reporting Information [Line Items]
Net income (loss)	(1.6)			(1.0)			(5.0)	(4.0)
Net income (loss) attributable to Hess Midstream Partners LP	(1.6)			(1.0)			(5.0)	(4.0)
Interest expense, net	0.6			0.3			1.6	1.0
Adjusted EBITDA	(1.0)			(0.7)			(3.4)	(3.0)
Adjusted EBITDA attributable to Hess Midstream Partners LP	(1.0)			(0.7)			(3.4)	(3.0)
Gathering Opco \| Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income	86.4			82.6			245.6	243.0
Net income (loss)	44.9			49.9			128.6	148.6
Net income (loss) attributable to Hess Midstream Partners LP	9.1			10.1			25.8	29.8
Depreciation expense	19.3			15.6			55.6	46.2
Adjusted EBITDA	64.2			65.5			184.2	194.8
Adjusted EBITDA attributable to Hess Midstream Partners LP	13.0			13.2			37.0	38.9
Capital expenditures	85.9			79.4			236.7	187.7
Processing and Storage \| Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income	74.0			65.2			208.0	186.4
Net income (loss)	42.8			39.6			124.2	111.0
Net income (loss) attributable to Hess Midstream Partners LP	8.8			8.1			25.4	22.8
Depreciation expense	11.2			11.0			33.5	32.8
Proportional share of equity affiliates' depreciation	0.5						0.5
Adjusted EBITDA	54.5			50.6			158.2	143.8
Adjusted EBITDA attributable to Hess Midstream Partners LP	11.0			10.3			32.0	29.4
Capital expenditures	15.0			0.5			23.7	7.9
Terminaling and Export \| Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income	35.0			21.7			88.8	61.8
Net income (loss)	14.3			8.3			38.8	24.8
Net income (loss) attributable to Hess Midstream Partners LP	2.8			1.6			7.8	5.0
Depreciation expense	4.0			4.0			12.0	11.8
Adjusted EBITDA	18.3			12.3			50.8	36.6
Adjusted EBITDA attributable to Hess Midstream Partners LP	3.6			2.4			10.2	7.4
Capital expenditures	$ 0.4			$ 1.1			$ 0.1	$ 3.3

Segments - Total Assets for Reportable Segments (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 3,005.3	$ 2,819.7
Interest and Other
Segment Reporting Information [Line Items]
Total assets	5.1	23.2
Gathering Opco \| Operating Segments
Segment Reporting Information [Line Items]
Total assets	1,649.4	1,467.7
Processing and Storage \| Operating Segments
Segment Reporting Information [Line Items]
Total assets	1,037.9	1,008.6
Terminaling and Export \| Operating Segments
Segment Reporting Information [Line Items]
Total assets	$ 312.9	$ 320.2

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions				3 Months Ended
	Oct. 24, 2019	Oct. 21, 2019	Oct. 04, 2019	Dec. 31, 2019
Forecast
Subsequent Event [Line Items]
Limited partner units to be issued				230
Percentage of ownership interest after proposed transaction				100.00%
Additional borrowings at close of transaction				$ 960,000,000
Total debt at close of transaction				1,770,000,000
Forecast \| Maximum
Subsequent Event [Line Items]
Issuance of senior notes				800,000,000
Forecast \| Hess and GIP
Subsequent Event [Line Items]
Cash consideration				$ 550,000,000
Percentage of exchangeable from class B units into class A shares				100.00%
Forecast \| Existing Public Unitholders
Subsequent Event [Line Items]
Conversion percentage of common unit into class A share of limited partner interest				100.00%
Forecast \| Public Shareholders
Subsequent Event [Line Items]
Percentage of ownership interest after proposed transaction				6.00%
Forecast \| Hess Corporation
Subsequent Event [Line Items]
Percentage of ownership interest after proposed transaction				47.00%
Forecast \| GIP II Blue Holding Partnership, LP
Subsequent Event [Line Items]
Percentage of ownership interest after proposed transaction				47.00%
Forecast \| HIP’s Joint Interest Assets
Subsequent Event [Line Items]
Percentage of ownership interest acquired				80.00%
Forecast \| HIP’s Water Services Business, and Outstanding Economic General Partner Interest and Incentive Distribution Rights
Subsequent Event [Line Items]
Percentage of ownership interest acquired				100.00%
Forecast \| Hess Infrastructure Partners LP
Subsequent Event [Line Items]
Business combination, liabilities assumed, debt				$ 1,150,000,000
Credit facilities retired with proposed transaction				355,000,000
Consent payment				2,000,000
Forecast \| Hess Infrastructure Partners LP \| Notes
Subsequent Event [Line Items]
Business combination, liabilities assumed, debt				$ 800,000,000
Subsequent Event
Subsequent Event [Line Items]
Quarterly cash distribution declared date	Oct. 24, 2019
Quarterly cash distribution declared per common and subordinated unit	$ 0.4112
Distribution made to limited partner, increase in percentage than prior year quarter declared	15.00%
Distribution Date	Nov. 13, 2019
Record Date	Nov. 04, 2019
Definitive agreement date			Oct. 04, 2019
Additional borrowings at close of transaction			$ 960,000,000
Total debt at close of transaction			1,770,000,000
Subsequent Event \| Maximum
Subsequent Event [Line Items]
Issuance of senior notes			800,000,000
Subsequent Event \| Hess Infrastructure Partners LP
Subsequent Event [Line Items]
Percentage of principal amount of notes have been validly tendered and not validly withdrawn pursuant to exchange offer		99.32%
Subsequent Event \| Hess Infrastructure Partners LP \| Notes
Subsequent Event [Line Items]
Business combination, liabilities assumed, debt			$ 800,000,000