Supplemental Quarterly Financial Information (Unaudited) - Schedule of Supplemental Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 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	[1]	Dec. 31, 2017	[1]
Quarterly Financial Information [Line Items]
Revenues and other income	$ 253.5	$ 214.9	$ 190.3	$ 189.6	$ 185.9	$ 183.8	$ 176.5	$ 166.5	$ 848.3	$ 712.7		$ 579.5
Income from operations	90.3	99.3	91.2	95.8	92.1	99.0	96.3	90.8	376.6	378.2		263.1
Net income	75.1	87.4	74.4	80.8	78.9	86.1	82.8	77.7	317.7	325.5		242.0
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		$ 41.2
Common Class A
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	$ 0.28
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		$ 0.75
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		$ 0.75

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