Related Party Transactions (Details) - Flatonia Energy, LLC - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Payments made to related party	$ 6,100,000	$ 7,200,000	$ 12,400,000	$ 14,400,000
Payments received from related party	2,000,000	$ 800,000	4,100,000	$ 2,400,000
Amounts receivable from related party	300,000		300,000		$ 1,300,000
Amounts payable to related party	$ 0		$ 0		$ 0
Class A Common Stock
Related Party Transaction [Line Items]
Percentage of common stock acquired			10.50%
Common Stock
Related Party Transaction [Line Items]
Percentage of common stock acquired			4.70%