Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015	Jun. 30, 2014
Revenues
Oil, Gas and NGL Sales	$ 722		$ 1,338		$ 1,462	$ 2,665
Income from Equity Method Investees	6		45		24	97
Other	2		0		4	0
Total	730		1,383		1,490	2,762
Costs and Expenses
Production Expense	213		244		459	474
Exploration Expense	41		59		106	133
Depreciation, Depletion and Amortization	451		413		905	837
General and Administrative	104		127		198	266
Asset Impairments	15		34		43	131
Other Operating (Income) Expense, Net	67		(23)		73	(12)
Total	891		854		1,784	1,829
Operating Income (Loss)	(161)		529		(294)	933
Other (Income) Expense
(Gain) Loss on Commodity Derivative Instruments	87		236		(63)	311
Interest, Net of Amount Capitalized	54		52		112	99
Other Non-Operating (Income) Expense, Net	(9)		8		(9)	13
Total	132		296		40	423
Income (Loss) Before Income Taxes	(293)		233		(334)	510
Income Tax (Benefit) Provision	(184)		41		(203)	118
Net Income (Loss)	$ (109)		$ 192		$ (131)	$ 392
Earnings Per Share, Basic [Abstract]
Net Income (in dollars per share)	$ (0.28)		$ 0.53		$ (0.35)	$ 1.09
Earnings Per Share, Diluted [Abstract]
Net Income (in dollars per share)	$ (0.28)		$ 0.52		$ (0.35)	$ 1.07
Weighted Average Number of Shares Outstanding [Abstract]
Weighted Average Number of Shares Outstanding, Basic (in shares)	387	[1]	361	[1]	378	361
Weighted Average Number of Shares Outstanding, Diluted (in shares)	387		366		378	365

[1] The weighted average number of shares outstanding includes the weighted average shares of common stock issued in connection with the underwritten public offering of 24,150,000 shares of common stock of the Company in first quarter 2015.