CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Millions, $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Revenues
Affiliate services		$ 264.7	$ 214.9	[1]	$ 825.1	$ 594.5	[1]
Type of Revenue [Extensible List]		hesm:AffiliateServicesMember	hesm:AffiliateServicesMember	[1]	hesm:AffiliateServicesMember	hesm:AffiliateServicesMember	[1]
Other income		$ 0.1			$ 0.3	$ 0.3	[1]
Total revenues		264.8	$ 214.9	[1]	825.4	594.8	[1]
Costs and expenses
Operating and maintenance expenses (exclusive of depreciation shown separately below)		83.9	71.9	[1]	270.8	184.1	[1]
Depreciation expense		39.5	36.0	[1]	116.9	105.0	[1]
General and administrative expenses		4.2	7.7	[1]	15.9	19.4	[1]
Total costs and expenses		127.6	115.6	[1]	403.6	308.5	[1]
Income from operations		137.2	99.3	[1]	421.8	286.3	[1]
Income from equity investments		3.6	0.5	[1]	7.2	0.5	[1]
Interest expense, net		23.2	12.4	[1]	71.3	44.2	[1]
Gain on sale of property, plant and equipment					0.1
Income before income tax expense (benefit)		117.6	87.4	[1]	357.8	242.6	[1]
Income tax expense (benefit)		1.8			5.2
Net income		115.8	87.4	[1]	352.6	242.6	[1]
Less: Net income (loss) attributable to net parent investment	[1]		(13.0)			(44.0)
Less: Net income (loss) attributable to noncontrolling interest		110.2	81.3	[1]	335.2	232.6	[1]
Net income attributable to Hess Midstream LP		5.6	19.1	[1]	17.4	54.0	[1]
Less: General partner's interest in net income	[1]		1.3			3.1
Limited partners' interest in net income		$ 5.6	$ 17.8	[1]	$ 17.4	$ 50.9	[1]
Common Units
Net income attributable to Hess Midstream LP per limited partner unit (basic and diluted):
Net income attributable to Hess Midstream Partners per limited partner unit	[1]		$ 0.33			$ 0.93
Weighted average limited partner units outstanding prior to the Restructuring, Basic:
Units outstanding prior to the Restructuring, Basic	[1]		27.3			27.3
Weighted average limited partner units outstanding prior to the Restructuring, Diluted:
Units outstanding prior to the Restructuring, Diluted	[1]		27.5			27.5
Subordinated Units
Net income attributable to Hess Midstream LP per limited partner unit (basic and diluted):
Net income attributable to Hess Midstream Partners per limited partner unit	[1]		$ 0.33			$ 0.93
Weighted average limited partner units outstanding prior to the Restructuring, Basic:
Units outstanding prior to the Restructuring, Basic	[1]		27.3			27.3
Weighted average limited partner units outstanding prior to the Restructuring, Diluted:
Units outstanding prior to the Restructuring, Diluted	[1]		27.3			27.3
Class A Shares
Net income attributable to Hess Midstream LP per Class A share:
Net income attributable to Hess Midstream LP per Class A share, Basic		$ 0.31			$ 0.97
Net income attributable to Hess Midstream LP per Class A share, Diluted		$ 0.31			$ 0.95
Net income attributable to Hess Midstream LP per limited partner unit (basic and diluted):
Weighted average Class A shares outstanding subsequent to the restructuring, Basic		18.0			18.0
Weighted average Class A shares outstanding subsequent to the restructuring, Diluted		18.1			18.1

[1] The financial information presented in this report has been retrospectively adjusted for the acquisition of Hess Infrastructure Partners LP.