Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 472,918	$ 370,395
Natural gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	472,859	370,340
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 59	$ 55

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details