Change in Accounting Principle - Statement of Consolidated Cash Flow (Details) - USD ($) $ in Millions		3 Months Ended										12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
NET LOSS INCLUDING NONCONTROLLING INTEREST		$ (143)	$ (559)	$ (200)	$ (371)		$ (4,428)		$ (4,136)	$ (797)	$ (1,306)	$ (1,273)		$ (10,667)	[1],[2],[3],[4]	$ (8,019)	[1],[2],[3],[4]
Loss (income) from discontinued operations												33		(492)	[2],[3]	1,707	[2],[3]
Loss (gain) on divestitures		0	(5)	(17)	1		(77)		5	(227)	18	(21)		(281)	[2],[3]	1,608	[2],[3]
Exploratory dry hole expense and unproved leasehold impairments												353		2,595	[3]	2,294	[3]
Depreciation, depletion, and amortization												2,618		3,300	[3]	4,526	[3]
Impairments		144	$ 951	$ 238	42		5,100		$ 4,100	$ 660	2,100	1,103		9,472	[2],[3]	7,102	[2],[3]
Other noncash items, net												164		7	[3]	(231)	[3]
Deferred income tax benefit												(833)		(1,445)	[2],[3]	(1,799)	[2],[3]
Changes in operating assets and liabilities												153		(80)		(329)
CASH PROVIDED BY CONTINUING OPERATING ACTIVITIES												2,453		2,554	[3]	7,013	[3]
CASH PROVIDED BY (USED IN) DISCONTINUED OPERATIONS												(23)		113	[3]	944	[3]
Additions to oil and gas property												(1,610)		(4,208)	[3]	(8,608)	[3]
Net cash provided by (used in) investing activities - continuing operations												(1,660)		(3,289)	[3]	(8,171)	[3]
NET CASH PROVIDED BY (USED IN) DISCONTINUED OPERATIONS												0		4,372	[3]	(219)	[3]
Other												(7)		53	[3]	49	[3]
Net cash used in financing activities												(860)		(2,962)	[3]	(794)	[3]
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS												(90)		788	[3]	(1,227)	[3]
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	[3]				1,467	[5]					679	1,467	[5]	679		1,906
CASH AND CASH EQUIVALENTS AT END OF PERIOD		1,377					1,467	[3],[5]				1,377		1,467	[3],[5]	679	[3]
Under Full Cost [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
NET LOSS INCLUDING NONCONTROLLING INTEREST												(1,394)		(23,528)		(5,060)
Loss (income) from discontinued operations												33		771		1,588
Loss (gain) on divestitures												(17)		(59)		180
Exploratory dry hole expense and unproved leasehold impairments												0		0		0
Depreciation, depletion, and amortization												3,570		29,372		9,720
Impairments												677		1,920		1,919
Other noncash items, net														161
Deferred income tax benefit												(721)		(5,778)		(514)
Changes in operating assets and liabilities												138		(170)		(239)
CASH PROVIDED BY CONTINUING OPERATING ACTIVITIES												2,606		2,834		7,517
CASH PROVIDED BY (USED IN) DISCONTINUED OPERATIONS														150		944
Additions to oil and gas property												(1,776)		(4,578)		(9,022)
Net cash provided by (used in) investing activities - continuing operations												(1,826)		(3,659)		(8,585)
NET CASH PROVIDED BY (USED IN) DISCONTINUED OPERATIONS														4,335		(219)
Other												6
Net cash used in financing activities												(847)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS												(90)		698		(1,137)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR					1,467						769	1,467		769		1,906
CASH AND CASH EQUIVALENTS AT END OF PERIOD		1,377					1,467					1,377		1,467		769
Change from Full Cost Method to Successful Efforts Method [Member] | Changes [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
NET LOSS INCLUDING NONCONTROLLING INTEREST												121		12,861		(2,959)
Loss (income) from discontinued operations												0		(1,263)		119
Loss (gain) on divestitures												(4)		(222)		1,428
Exploratory dry hole expense and unproved leasehold impairments												353		2,595		2,294
Depreciation, depletion, and amortization												(952)		(26,072)		(5,194)
Impairments												426		7,552		5,183
Other noncash items, net														(154)
Deferred income tax benefit												(112)		4,333		(1,285)
Changes in operating assets and liabilities												15		90		(90)
CASH PROVIDED BY CONTINUING OPERATING ACTIVITIES												(153)		(280)		(504)
CASH PROVIDED BY (USED IN) DISCONTINUED OPERATIONS														(37)		0
Additions to oil and gas property												166		370		414
Net cash provided by (used in) investing activities - continuing operations												166		370		414
NET CASH PROVIDED BY (USED IN) DISCONTINUED OPERATIONS														37		0
Other												(13)
Net cash used in financing activities												(13)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS												0		90		(90)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR					$ 0						$ (90)	0		(90)		0
CASH AND CASH EQUIVALENTS AT END OF PERIOD		$ 0					$ 0					$ 0		$ 0		$ (90)

[1] Financial information for 2015 and 2014 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.

[2] Financial information for 2015 and 2014 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.

[3] Financial information for 2015 and 2014 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.

[4] Financial information for 2015, 2014, and 2013 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.

[5] Financial information for 2015 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.