Segments - Financial Data for Each Reportable Segment (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenues and other income		$ 288.8	$ 290.8
Net income (loss)		159.6	129.0
Net income (loss) attributable to Hess Midstream LP		8.6	6.5
Depreciation expense		40.2	38.5
Proportional share of equity affiliates' depreciation		1.3	1.3
Income from equity investments		2.7	2.7
Interest expense, net		23.1	24.8
Income tax expense		2.5	1.7
Adjusted EBITDA		226.7	195.3
Capital expenditures	[1]	23.1	57.0
Interest and Other
Segment Reporting Information [Line Items]
Net income (loss)		(27.7)	(30.3)
Net income (loss) attributable to Hess Midstream LP		(4.2)	(3.6)
Interest expense, net		23.1	24.8
Income tax expense		2.5	1.7
Adjusted EBITDA		(2.1)	(3.8)
Gathering Opco | Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income		152.7	141.6
Net income (loss)		92.4	75.9
Net income (loss) attributable to Hess Midstream LP		6.4	4.8
Depreciation expense		24.9	23.3
Adjusted EBITDA		117.3	99.2
Capital expenditures	[1]	19.4	15.8
Processing and Storage | Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income		103.5	97.0
Net income (loss)		70.9	62.7
Net income (loss) attributable to Hess Midstream LP		4.8	4.0
Depreciation expense		11.2	11.2
Proportional share of equity affiliates' depreciation		1.3	1.3
Income from equity investments		2.7	2.7
Adjusted EBITDA		83.4	75.2
Capital expenditures	[1]	3.7	41.1
Terminaling and Export | Operating Segments
Segment Reporting Information [Line Items]
Revenues and other income		32.6	52.2
Net income (loss)		24.0	20.7
Net income (loss) attributable to Hess Midstream LP		1.6	1.3
Depreciation expense		4.1	4.0
Adjusted EBITDA		$ 28.1	24.7
Capital expenditures	[1]		$ 0.1

[1] Includes acquisition, expansion and maintenance capital expenditures, as applicable