Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Number of days in which payment is required									25 days
Contract with customer, asset, net	$ 384,000				$ 783,000				$ 384,000	$ 783,000
Due from joint ventures	127,900				324,200				127,900	324,200
Sales of natural gas, natural gas liquids and oil									3,791,414	4,709,384
Loss on derivatives not designated as hedges									616,634	(178,591)	$ 390,021
Total operating revenues	$ 1,011,483	$ 951,576	$ 1,310,252	$ 1,143,173	$ 1,245,138	$ 1,050,046	$ 950,648	$ 1,312,036	4,416,484	4,557,868	$ 3,091,020
Natural Gas Sales
Disaggregation of Revenue [Line Items]
Sales of natural gas, natural gas liquids and oil									3,559,809	4,217,684
NGLs Sales
Disaggregation of Revenue [Line Items]
Sales of natural gas, natural gas liquids and oil									197,985	442,010
Oil Sales
Disaggregation of Revenue [Line Items]
Sales of natural gas, natural gas liquids and oil									33,620	35,825
Net Marketing Services and Other
Disaggregation of Revenue [Line Items]
Sales of natural gas, natural gas liquids and oil									0	13,865
Net marketing services and other									$ 8,436	$ 27,075