Related Party Transactions (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Flatonia Energy, LLC
Related Party Transaction [Line Items]
Payments made to related party		$ 3.8	$ 0.0	$ 12.1	$ 12.4
Payments received from related party		2.0	$ 0.7	4.9	$ 4.8
Amounts receivable from related party		0.3		0.3		$ 0.8
Amounts payable to related party		$ 1.1		$ 1.1		$ 1.6
Flatonia Energy, LLC | Class A Common Stock
Related Party Transaction [Line Items]
Percentage of common stock acquired				10.10%
Flatonia Energy, LLC | Common Class A and Common Class B
Related Party Transaction [Line Items]
Percentage of common stock acquired				4.60%
Subsequent Event
Related Party Transaction [Line Items]
Payments received from related party	$ 3.6