Earnings per Share - Schedule of Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Limited Partners Capital Account [Line Items]
Net income	$ 159.6	$ 129.0
Less: Net income attributable to noncontrolling interest	151.0	122.5
Net income attributable to Hess Midstream LP	8.6	6.5
Class A Shares
Limited Partners Capital Account [Line Items]
Net income	$ 8.6	$ 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	$ 0.45	$ 0.37
Net income attributable to Hess Midstream LP per Class A share, Diluted	$ 0.43	$ 0.35
Weighted average Class A shares outstanding
Weighted average Class A shares outstanding, Basic	19.3	18.0
Weighted average Class A shares outstanding, Diluted	19.4	18.0