Acquisitions - Consolidated Statements of Operations (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Revenues and other income
Affiliate services										$ 847.6	$ 712.0	[1]	$ 579.5	[1]
Type of Revenue [Extensible List]										hesm:AffiliateServicesMember	hesm:AffiliateServicesMember	[1]	hesm:AffiliateServicesMember	[1]
Other income										$ 0.7	$ 0.7	[1]
Total revenues		$ 253.5	$ 214.9	$ 190.3	$ 189.6	$ 185.9	$ 183.8	$ 176.5	$ 166.5	848.3	712.7	[1]	$ 579.5	[1]
Costs and expenses
Operating and maintenance expenses (exclusive of depreciation shown separately below)										276.8	193.5	[1]	186.0	[1]
Depreciation expense										142.5	126.9	[1]	116.5	[1]
General and administrative expenses										52.4	14.1	[1]	13.9	[1]
Total costs and expenses										471.7	334.5	[1]	316.4	[1]
Income from operations		90.3	99.3	91.2	95.8	92.1	99.0	96.3	90.8	376.6	378.2	[1]	263.1	[1]
Interest expense, net										62.4	53.3	[1]	25.8	[1]
Gain on sale of property, plant and equipment	[1]										0.6		4.7
Net income		75.1	87.4	74.4	80.8	78.9	86.1	82.8	77.7	317.7	325.5	[1]	242.0	[1]
Less: Net income (loss) attributable to net parent investment										(55.0)	(46.8)	[1]	25.4	[1]
Less: Net income (loss) attributable to noncontrolling interest										302.6	301.5	[1]	175.4	[1]
Net income attributable to Hess Midstream LP		$ 16.1	$ 19.1	$ 16.8	$ 18.1	$ 17.2	$ 18.8	$ 17.8	$ 17.0	70.1	70.8	[1]	41.2	[1]
Less: General partner's interest in net income prior to the Restructuring										3.4	1.7	[1]	0.8	[1]
Limited partners' interest in net income										$ 66.7	69.1	[1]	40.4	[1]
Partnership as Previously Reported
Revenues and other income
Affiliate services											$ 661.7		$ 565.6
Type of Revenue [Extensible List]											hesm:AffiliateServicesMember		hesm:AffiliateServicesMember
Other income											$ 0.7		$ 0.2
Total revenues											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 (loss) attributable to net parent investment													68.2
Less: Net income (loss) attributable to noncontrolling interest											301.5		175.4
Net income attributable to Hess Midstream LP											70.8		41.2
Less: General partner's interest in net income prior to the Restructuring											1.7		0.8
Limited partners' interest in net income											69.1		40.4
Restatement Adjustment | Acquisition of HIP
Revenues and other income
Affiliate services											$ 50.3		$ 13.9
Type of Revenue [Extensible List]											hesm:AffiliateServicesMember		hesm:AffiliateServicesMember
Other income													$ (0.2)
Total revenues											$ 50.3		13.7
Costs and expenses
Operating and maintenance expenses (exclusive of depreciation shown separately below)											39.2		27.6
Depreciation expense											3.9		3.4
General and administrative expenses											2.6		5.8
Total costs and expenses											45.7		36.8
Income from operations											4.6		(23.1)
Interest expense, net											52.0		24.4
Gain on sale of property, plant and equipment											0.6		4.7
Net income											(46.8)		(42.8)
Less: Net income (loss) attributable to net parent investment											$ (46.8)		$ (42.8)
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			$ 0.33	$ 0.29	$ 0.32	$ 0.31	$ 0.34	$ 0.32	$ 0.30		$ 1.27	[1]	$ 0.75	[1]
Weighted average limited partner units outstanding, Basic:
Units outstanding prior to the Restructuring, Basic										27.3	27.3	[1]	26.9	[1]
Weighted average limited partner units outstanding, Diluted:
Units outstanding prior to the Restructuring, Diluted										27.5	27.4	[1]	26.9	[1]
Weighted average limited partner units outstanding (basic and diluted):
Weighted average Class A shares outstanding subsequent to the Restructuring (basic and diluted):													26.9
Common Units | Partnership as Previously Reported
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											$ 1.27		$ 0.75
Weighted average limited partner units outstanding, Basic:
Units outstanding prior to the Restructuring, Basic											27.3
Weighted average limited partner units outstanding, Diluted:
Units outstanding prior to the Restructuring, Diluted											27.4
Weighted average limited partner units outstanding (basic and diluted):
Weighted average Class A shares outstanding subsequent to the Restructuring (basic and diluted):													26.9
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			$ 0.33	$ 0.29	$ 0.32	$ 0.31	$ 0.34	$ 0.32	$ 0.30		$ 1.27	[1]	$ 0.75	[1]
Weighted average limited partner units outstanding, Basic:
Units outstanding prior to the Restructuring, Basic										27.3	27.3	[1]	26.9	[1]
Weighted average limited partner units outstanding, Diluted:
Units outstanding prior to the Restructuring, Diluted										27.3	27.3	[1]	26.9	[1]
Weighted average limited partner units outstanding (basic and diluted):
Weighted average Class A shares outstanding subsequent to the Restructuring (basic and diluted):													26.9
Subordinated Units | Partnership as Previously Reported
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											$ 1.27		$ 0.75
Weighted average limited partner units outstanding, Basic:
Units outstanding prior to the Restructuring, Basic											27.3
Weighted average limited partner units outstanding, Diluted:
Units outstanding prior to the Restructuring, Diluted											27.3
Weighted average limited partner units outstanding (basic and diluted):
Weighted average Class A shares outstanding subsequent to the Restructuring (basic and diluted):													26.9

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