Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Total Operating Revenues and Other	$ 2,965,498	$ 2,245,484	$ 1,103,374	$ 4,717,692	$ 4,320,246	$ 4,303,455	$ 4,697,630	$ 4,058,642	$ 11,032,048		$ 17,379,973		$ 17,275,399
Gathering and Processing Costs									459,211	[1]	479,102	[1]	436,973
Marketing Costs									2,697,729		5,351,524		5,203,243
Total Operating Expenses									11,576,064		13,680,962		12,806,053
Operating Income	487,662	$ (2,714)	$ (1,086,549)	$ 57,585	863,751	$ 827,959	$ 1,130,771	$ 876,530	(544,016)		3,699,011		4,469,346
Accounts Receivable From Contracts With Customers	1,337,000				$ 1,619,000				1,337,000		1,619,000		1,460,000
Revolving Credit Agreement (New Facility)
Maximum borrowing capacity	$ 2,000,000								2,000,000
Crude Oil and Condensate
Revenues									5,785,609		9,612,532		9,517,440
Natural Gas Liquids
Revenues									667,514		784,818		1,127,510
Natural Gas
Revenues									837,133		1,184,095		1,301,537
Gathering, Processing and Marketing
Revenues									$ 2,582,984		$ 5,360,282		5,230,355
Accounting Standards Update 2014-09 [Member]
Total Operating Revenues and Other													17,052,465
Gathering and Processing Costs													233,258
Marketing Costs													5,184,024
Total Operating Expenses													12,583,119
Operating Income													4,469,346
Accounting Standards Update 2014-09 [Member] | Crude Oil and Condensate
Revenues													9,517,440
Accounting Standards Update 2014-09 [Member] | Natural Gas Liquids
Revenues													1,121,237
Accounting Standards Update 2014-09 [Member] | Natural Gas
Revenues													1,104,095
Accounting Standards Update 2014-09 [Member] | Gathering, Processing and Marketing
Revenues													5,211,136
Effect of Change [Member]
Total Operating Revenues and Other													222,934
Gathering and Processing Costs													203,715
Marketing Costs													19,219
Total Operating Expenses													222,934
Operating Income													0
Effect of Change [Member] | Crude Oil and Condensate
Revenues													0
Effect of Change [Member] | Natural Gas Liquids
Revenues													6,273
Effect of Change [Member] | Natural Gas
Revenues													197,442
Effect of Change [Member] | Gathering, Processing and Marketing
Revenues													$ 19,219

[1] Excludes gains or losses on the mark-to-market of financial commodity derivative contracts, gains or losses on sales of reserves and related assets, interest charges and general corporate expenses for each of the three years in the period ended December 31, 2020.