Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018
Crude Oil and Condensate	$ 2,377,528	$ 1,445,454	$ 4,478,836	$ 2,875,515
Natural Gas Liquids	286,354	146,907	507,769	300,351
Natural Gas	300,845	224,008	600,611	454,610
Gathering, Processing and Marketing	1,436,436	778,797	2,538,258	1,505,334
Total Operating Revenues and Other	4,238,077	2,612,472	7,919,239	5,223,037
Gathering and Processing Costs	109,169		210,514
Marketing Costs	1,420,463	790,599	2,526,853	1,527,135
Total Operating Expenses	3,273,146	2,484,564	6,079,720	4,987,383
Operating Income (Loss)	964,931	$ 127,908	1,839,519	$ 235,654
Accounts Receivable From Contracts With Customers	1,608,000		1,608,000		$ 1,343,000
Amounts Without Adoption of ASU 2014-09 [Member]
Crude Oil and Condensate	2,377,528		4,478,836
Natural Gas Liquids	284,898		504,543
Natural Gas	257,652		514,273
Gathering, Processing and Marketing	1,431,077		2,527,313
Total Operating Revenues and Other	4,188,069		7,818,730
Gathering and Processing Costs	64,520		120,950
Marketing Costs	1,415,104		2,515,908
Total Operating Expenses	3,223,138		5,979,211
Operating Income (Loss)	964,931		1,839,519
Effect of Change [Member]
Crude Oil and Condensate	0		0
Natural Gas Liquids	1,456		3,226
Natural Gas	43,193		86,338
Gathering, Processing and Marketing	5,359		10,945
Total Operating Revenues and Other	50,008		100,509
Gathering and Processing Costs	44,649		89,564
Marketing Costs	5,359		10,945
Total Operating Expenses	50,008		100,509
Operating Income (Loss)	$ 0		$ 0