Statement of Consolidated Operations - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Oil and gas production revenues:
Oil and gas production revenues	$ 6,383,000,000	$ 12,691,000,000	$ 14,771,000,000
Other	(17,000,000)	110,000,000	(333,000,000)
Total revenues and other	6,366,000,000	12,801,000,000	14,438,000,000
Oil and gas property and equipment
Depreciation, depletion and amortization	29,372,000,000	9,720,000,000	5,866,000,000
Asset retirement obligation accretion	145,000,000	154,000,000	211,000,000
Lease operating expenses	1,854,000,000	2,238,000,000	2,650,000,000
Gathering and transportation	211,000,000	273,000,000	288,000,000
Taxes other than income	282,000,000	577,000,000	772,000,000
Impairments	1,920,000,000	1,919,000,000	0
General and administrative	377,000,000	451,000,000	481,000,000
Transaction, reorganization, and separation	132,000,000	67,000,000	33,000,000
Financing costs, net	299,000,000	211,000,000	229,000,000
Total operating expenses	34,592,000,000	15,610,000,000	10,530,000,000
NET INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(28,226,000,000)	(2,809,000,000)	3,908,000,000
Current income tax provision	309,000,000	1,177,000,000	1,619,000,000
Deferred income tax provision (benefit)	(5,778,000,000)	(514,000,000)	309,000,000
NET INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTEREST	(22,757,000,000)	(3,472,000,000)	1,980,000,000
Net income (loss) from discontinued operations, net of tax	(771,000,000)	(1,588,000,000)	308,000,000
NET INCOME (LOSS) INCLUDING NONCONTROLLING INTEREST	(23,528,000,000)	(5,060,000,000)	2,288,000,000
Preferred stock dividends			44,000,000
Net income (loss) attributable to noncontrolling interest	(409,000,000)	343,000,000	56,000,000
Net income (loss) attributable to common shareholders	(23,119,000,000)	(5,403,000,000)	2,188,000,000
NET INCOME (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS:
Net income (loss) from continuing operations attributable to common shareholders	(22,348,000,000)	(3,815,000,000)	1,880,000,000
Net income (loss) from discontinued operations	(771,000,000)	(1,588,000,000)	308,000,000
Net income (loss) attributable to common shareholders	$ (23,119,000,000)	$ (5,403,000,000)	$ 2,188,000,000
BASIC NET INCOME (LOSS) PER COMMON SHARE:
Basic net income (loss) from continuing operations per share	$ (59.16)	$ (9.93)	$ 4.75
Basic net income (loss) from discontinued operations per share	(2.04)	(4.13)	0.78
Basic net income (loss) per share	(61.20)	(14.06)	5.53
DILUTED NET INCOME (LOSS) PER COMMON SHARE:
Diluted net income (loss) from continuing operations per share	(59.16)	(9.93)	4.74
Diluted net income (loss) from discontinued operations per share	(2.04)	(4.13)	0.76
Diluted net income (loss) per share	$ (61.20)	$ (14.06)	$ 5.50
WEIGHTED-AVERAGE NUMBER OF COMMON SHARES OUTSTANDING:
Basic	378	384	395
Diluted	378	384	406
DIVIDENDS DECLARED PER COMMON SHARE	$ 1.00	$ 1.00	$ 0.80
Other Assets [Member]
Oil and gas property and equipment
Depreciation, depletion and amortization	$ 324,000,000	$ 331,000,000	$ 337,000,000
Oil and Gas Property and Equipment Recurring [Member]
Oil and gas property and equipment
Depreciation, depletion and amortization	3,531,000,000	4,388,000,000	4,534,000,000
Oil and Gas Property and Equipment Additional [Member]
Oil and gas property and equipment
Depreciation, depletion and amortization	25,517,000,000	5,001,000,000	995,000,000
Oil Reserves [Member]
Oil and gas production revenues:
Revenues	4,999,000,000	10,040,000,000	11,853,000,000
Natural Gas [Member]
Oil and gas production revenues:
Revenues	1,157,000,000	1,983,000,000	2,266,000,000
Natural Gas Liquids [Member]
Oil and gas production revenues:
Revenues	$ 227,000,000	$ 668,000,000	$ 652,000,000