Significant Accounting Policies - Narrative (Details)	1 Months Ended			12 Months Ended
	Oct. 31, 2019 USD ($)	May 31, 2019 USD ($)	Apr. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) contract	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)	May 31, 2017 USD ($)
Property, Plant and Equipment [Line Items]
Financing receivable, gross		$ 58,000,000.0
Loss on secured term loan receivable				$ 52,900,000	$ 0	$ 0
Depreciation				490,700,000	453,800,000	418,200,000
Property, plant and equipment, disposals				12,400,000	2,100,000	8,400,000
Proceeds from sale of productive assets				14,300,000	1,700,000	2,300,000
Gain (loss) on disposition of assets				1,900,000	(400,000)	0
Expected proceeds from insurance settlements					6,100,000
Proceeds from sale of property				14,300,000	1,900,000	2,300,000
Tangible asset impairment charges				$ 7,900,000		17,100,000
Intangible asset, useful life				15 years
Provision for loss on contracts					9,000,000.0
Number of contracts, specified delivery | contract				1
Derivative, notional amount			$ 850,000,000.0
Derivative, fixed interest rate			2.27825%
Accumulated other comprehensive loss				$ 11,000,000.0	2,000,000.0			$ 2,200,000
Allowance for doubtful accounts receivable				500,000	300,000
Environmental remediation expense				0	0	$ 0
Debt issuance costs, noncurrent, net				29,800,000	24,500,000
Other assets, net				80,400,000
Lease liability (less than)				103,000,000.0
Louisiana
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges				24,600,000
Crude and Condensate
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges				109,200,000
Cedar Cove JV
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges				$ 31,400,000
Accounting Standards Update 2016-02
Property, Plant and Equipment [Line Items]
Other assets, net							$ 75,300,000
Lease liability (less than)							97,600,000
Other liabilities							$ (22,600,000)
Minimum
Property, Plant and Equipment [Line Items]
Intangible asset, useful life				5 years
Maximum
Property, Plant and Equipment [Line Items]
Intangible asset, useful life				20 years
EnLink Midstream Partners, LP
Property, Plant and Equipment [Line Items]
Gas balancing payable				$ 5,700,000	12,400,000
Gas balancing receivable				$ 6,400,000	10,400,000
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Decrease in revenue from contract with customer					$ (671,000,000.0)
Percentage decrease in revenue from contract with customer					8.00%
Delaware Basin JV | NPG
Property, Plant and Equipment [Line Items]
Noncontrolling interest, ownership percentage by parent				49.90%
Ascension JV | Marathon Petroleum and Resources LLC
Property, Plant and Equipment [Line Items]
Noncontrolling interest, ownership percentage by parent				50.00%
White Star
Property, Plant and Equipment [Line Items]
Financing receivable, scheduled payment	$ 10,750,000	$ 9,750,000	$ 19,500,000
Minimum Volume Contract [Member]
Property, Plant and Equipment [Line Items]
Contractual commitments				$ 154,000,000.0
Contract with customer, liability, revenue recognized				$ 19,700,000