Revenue Recognition - Revenues from Contracts with Customers Disaggregated by Product (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,985,469	$ 2,143,716	$ 1,747,293
Natural gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,985,240	1,881,150	1,506,078
Crude oil and condensate
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	48,722	212,338
Brokered natural gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	209,530	17,217
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 229	$ 4,314	$ 11,660