Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 411,788	$ 288,374	$ 884,706	$ 658,769
Natural gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	411,718	288,286	884,577	658,626
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 70	$ 88	$ 129	$ 143