Earnings per Share - Schedule of Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Limited Partners Capital Account [Line Items]
Net income	$ 162.0	$ 159.6	$ 107.8	$ 129.0	$ 321.6	$ 236.8
Less: Net income attributable to noncontrolling interest	151.0		102.5		302.0	225.0
Net income attributable to Hess Midstream LP	11.0		5.3		$ 19.6	$ 11.8
Class A Shares
Limited Partners Capital Account [Line Items]
Net income	$ 11.0	$ 8.6	$ 5.3	$ 6.5
Net income attributable to Hess Midstream LP per Class A share:
Net income attributable to Hess Midstream LP per Class A share, Basic	$ 0.44		$ 0.29		$ 0.89	$ 0.66
Net income attributable to Hess Midstream LP per Class A share, Diluted	$ 0.44		$ 0.29		$ 0.87	$ 0.64
Weighted average Class A shares outstanding
Weighted average Class A shares outstanding, Basic	25.0		18.0		22.2	18.0
Weighted average Class A shares outstanding, Diluted	25.1		18.1		22.3	18.1