CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Operating Revenues:
Operating Revenues	$ 3,862	$ 3,203		$ 2,436
Operating Costs and Expenses:
Operating expenses	785	671		592
General and administrative expenses	209	233		247
Restructuring charges	39			73
Depreciation, depletion and amortization	560	504		436
Impairments	171			2,321
Gain on sale of assets, net	(17)	(6)
Taxes, other than income taxes	89	94		93
Total Operating Costs and Expenses	3,065	2,472		4,626
Operating Income (Loss)	797	731		(2,190)
Interest Expense:
Interest on debt	231	239		226
Other interest charges	8	9		14
Interest capitalized	(115)	(113)		(152)
Total Interest Expense	124	135		88
Gain (Loss) on Derivatives	(118)	422		(339)
Loss on Early Extinguishment of Debt	(17)	(70)		(51)
Other Income (Loss), Net		5		(4)
Income (Loss) Before Income Taxes	538	953		(2,672)
Provision (Benefit) for Income Taxes:
Current	1	(22)		(7)
Deferred		(71)		(22)
Provision (Benefit) for Income Taxes	1	(93)		(29)
Net Income (Loss)	537	1,046	[1]	(2,643)
Mandatory convertible preferred stock dividend		108		108
Participating securities - mandatory convertible preferred stock	2	123
Net Income (Loss) Attributable to Common Stock	$ 535	$ 815		$ (2,751)
Earnings (Loss) Per Common Share:
Basic	$ 0.93	$ 1.64		$ (6.32)
Diluted	$ 0.93	$ 1.63		$ (6.32)
Weighted Average Common Shares Outstanding:
Basic	574,631,756	498,264,321		435,337,402
Diluted	576,642,808	500,804,297		435,337,402
Gas Sales [Member]
Operating Revenues:
Operating Revenues	$ 1,998	$ 1,793		$ 1,273
Oil Sales [Member]
Operating Revenues:
Operating Revenues	196	102		69
NGL Sales [Member]
Operating Revenues:
Operating Revenues	352	206		92
Marketing [Member]
Operating Revenues:
Operating Revenues	1,222	972		864
Gas Gathering [Member]
Operating Revenues:
Operating Revenues	89	126		138
Other [Member]
Operating Revenues:
Operating Revenues	5	4
Natural Gas, Gathering, Transportation, Marketing and Processing [Member]
Operating Costs and Expenses:
Marketing purchases	$ 1,229	$ 976		$ 864

[1] In 2018 and 2017, deferred tax activity incurred in other comprehensive income was offset by a valuation allowance.