Acquisitions - Consolidated Statements of Cash Flows (Detail) - USD ($) $ 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
Cash flows from operating activities
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]
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense											142.5	126.9	[1]	116.5	[1]
(Gain) loss on sale of property, plant and equipment	[1]											(0.6)		(4.7)
(Gain) loss on interest rate swaps											(0.8)	(0.4)	[1]	(1.7)	[1]
Amortization of deferred financing costs											5.1	5.0	[1]	3.8	[1]
Unit-based compensation											1.5	0.9	[1]	0.2	[1]
Changes in assets and liabilities:
Accounts receivable – affiliate											(19.5)	(6.3)	[1]	(16.9)	[1]
Other current and noncurrent assets											(1.4)	1.9	[1]	1.2	[1]
Accounts payable – trade											11.5	4.0	[1]	(16.7)	[1]
Accounts payable – affiliate											3.7	(6.4)	[1]	7.5	[1]
Accrued liabilities											18.6	17.3	[1]	3.2	[1]
Other current and noncurrent liabilities											(0.6)	(0.9)	[1]	2.1	[1]
Net cash provided by (used in) operating activities											470.7	466.9	[1]	336.5	[1]
Cash flows from investing activities
Payments for equity investments											(33.0)	(67.3)	[1]
Proceeds from sale of property, plant and equipment	[1]											1.6		12.8
Additions to property, plant and equipment											(306.4)	(241.9)	[1]	(144.2)	[1]
Net cash provided by (used in) investing activities											(497.5)	(307.6)	[1]	(131.4)	[1]
Cash flows from financing activities
Proceeds from (repayments of) bank borrowings - revolver											32.0			(153.0)	[1]
Repayments of bank borrowings - term loan												(2.5)		(385.0)
Proceeds from issuance of fixed-rate senior notes											550.0			800.0	[1]
Financing costs											(20.4)	(1.0)	[1]	(22.9)	[1]
IPO proceeds, net of underwriters' discounts	[1]													365.5
Distribution of IPO proceeds to Hess and GIP														(349.5)
Cash offering costs	[1]													(2.1)
Distributions to Hess and GIP												(322.0)		(100.0)
Distributions to HESM limited partners											(85.4)	(74.1)	[1]	(31.7)	[1]
Other contributions (distributions)	[1]											(6.1)		27.6
Net cash provided by (used in) financing activities											(79.2)	(405.7)	[1]	148.9	[1]
Increase (decrease) in cash and cash equivalents											(106.0)	(246.4)	[1]	354.0	[1]
Cash and cash equivalents, beginning of period	[1]				109.3					355.7	109.3	355.7		1.7
Cash and cash equivalents, end of period		$ 3.3				109.3	[1]				3.3	109.3	[1]	355.7	[1]
Partnership as Previously Reported
Cash flows from operating activities
Net income												372.3		284.8
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense												123.0		113.1
Amortization of deferred financing costs												1.0		0.6
Unit-based compensation												0.9		0.2
Changes in assets and liabilities:
Accounts receivable – affiliate												(3.2)		(15.2)
Other current and noncurrent assets												1.6		(1.7)
Accounts payable – trade												3.1		(16.6)
Accounts payable – affiliate												(6.7)		34.4
Accrued liabilities												2.7		(1.9)
Other current and noncurrent liabilities												(1.1)		2.2
Net cash provided by (used in) operating activities												493.6		399.9
Cash flows from investing activities
Payments for equity investments												(67.3)
Additions to property, plant and equipment												(235.6)		(136.4)
Net cash provided by (used in) investing activities												(302.9)		(136.4)
Cash flows from financing activities
Cash distributions to parent prior to the IPO on April 10, 2017														(95.3)
Cash contributions from parent prior to the IPO on April 10, 2017														67.1
Financing costs														(3.9)
IPO proceeds, net of underwriters' discounts														365.5
Distribution of IPO proceeds to Hess and GIP														(349.5)
Cash offering costs														(2.1)
Distributions to noncontrolling interest												(199.2)		(244.6)
Contributions from noncontrolling interests												57.3		78.5
Distributions to HESM limited partners												(74.1)		(31.7)
Distributions to HESM general partner												(1.6)		(0.6)
Net cash provided by (used in) financing activities												(217.6)		(216.6)
Increase (decrease) in cash and cash equivalents												(26.9)		46.9
Cash and cash equivalents, beginning of period					20.3					47.2	20.3	47.2		0.3
Cash and cash equivalents, end of period						20.3						20.3		47.2
Restatement Adjustment | Acquisition of HIP
Cash flows from operating activities
Net income												(46.8)		(42.8)
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense												3.9		3.4
(Gain) loss on sale of property, plant and equipment												(0.6)		(4.7)
(Gain) loss on interest rate swaps												(0.4)		(1.7)
Amortization of deferred financing costs												4.0		3.2
Changes in assets and liabilities:
Accounts receivable – affiliate												(3.1)		(1.7)
Other current and noncurrent assets												0.3		2.9
Accounts payable – trade												0.9		(0.1)
Accounts payable – affiliate												0.3		(26.9)
Accrued liabilities												14.6		5.1
Other current and noncurrent liabilities												0.2		(0.1)
Net cash provided by (used in) operating activities												(26.7)		(63.4)
Cash flows from investing activities
Proceeds from sale of property, plant and equipment												1.6		12.8
Additions to property, plant and equipment												(6.3)		(7.8)
Net cash provided by (used in) investing activities												(4.7)		5.0
Cash flows from financing activities
Cash distributions to parent prior to the IPO on April 10, 2017														95.3
Cash contributions from parent prior to the IPO on April 10, 2017														(67.1)
Proceeds from (repayments of) bank borrowings - revolver														(153.0)
Repayments of bank borrowings - term loan												(2.5)		(385.0)
Proceeds from issuance of fixed-rate senior notes														800.0
Financing costs												(1.0)		(19.0)
Distributions to Hess and GIP												(322.0)		(100.0)
Distributions to noncontrolling interest												199.2		244.6
Contributions from noncontrolling interests												(57.3)		(78.5)
Distributions to HESM general partner												1.6		0.6
Other contributions (distributions)												(6.1)		27.6
Net cash provided by (used in) financing activities												(188.1)		365.5
Increase (decrease) in cash and cash equivalents												(219.5)		307.1
Cash and cash equivalents, beginning of period					$ 89.0					$ 308.5	$ 89.0	308.5		1.4
Cash and cash equivalents, end of period						$ 89.0						$ 89.0		$ 308.5

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