Significant Accounting Policies - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Revenues		$ (1,764,700,000)	$ (1,263,600,000)	$ (3,526,400,000)	$ (2,585,500,000)
Expected gross operating margin from long-term purchase commitment	$ 135,100,000
Amount due from counterparty due to deficiency on MVC	19,700,000
Total principal payments to be received	$ 58,000,000
Financing receivable, interest rate	8.00%
Overriding royalty interest percentage	1.00%
Consideration received due to restructuring of contract		45,500,000
Expired rights-of-ways and abandoned brine disposal well
Property, Plant and Equipment [Line Items]
Impairment of long-lived assets				0	$ 7,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Revenues		$ 163,000,000		$ 301,000,000
Percentage decrease in revenue from contracts with customers		9.00%		8.00%