Segment Information (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Segment Reporting Information [Line Items]
Sales and other operating revenues		$ 870		$ 1,307		$ 1,584		$ 2,587
Marketing revenues		89		183		147		387
Total revenues		959		1,490		1,731		2,974
Income from equity method investments		37		26		51		62
Net gain ( loss) on disposal of assets and other income		306		15		250		27
Production expenses		350		450		678		894
Marketing costs		88		182		146		387
Exploration Expenses		189		111		213		201
Depreciation, depletion and amortization		561		751		1,170		1,572
Impairments		0		44		1		44
Other expenses	[1]	227		249		487		527
Taxes other than income		39		78		87		145
Net interest and other		86		58		171		105
Income tax provision (benefit)		(68)		(6)		(344)		(150)
Segment income (loss) /Loss from continuing operations		(170)		(386)		(577)		(662)
Capital expenditures	[2]	177		678		536		1,780
Deferred Income Tax Expense (Benefit)						(392)		(185)
North America Exploration and Production [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues		617		993		1,110		1,843
Marketing revenues		53		110		84		288
Total revenues		670		1,103		1,194		2,131
Income from equity method investments		0		0		0		0
Net gain ( loss) on disposal of assets and other income		2		11		3		11
Production expenses		129		179		263		381
Marketing costs		52		112		84		292
Exploration Expenses		37		91		55		126
Depreciation, depletion and amortization		433		634		920		1,317
Impairments				0		1		0
Other expenses	[1]	97		99		215		216
Taxes other than income		35		67		77		128
Net interest and other		0		0		0		0
Income tax provision (benefit)		(41)		(23)		(153)		(112)
Segment income (loss) /Loss from continuing operations		(70)		(45)		(265)		(206)
Capital expenditures	[2]	153		551		468		1,484
International Exploration and Production [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues		159		211		255		393
Marketing revenues		23		30		38		56
Total revenues		182		241		293		449
Income from equity method investments		37		26		51		62
Net gain ( loss) on disposal of assets and other income		7		4		13		14
Production expenses		56		64		109		131
Marketing costs		23		29		37		54
Exploration Expenses		4		20		10		75
Depreciation, depletion and amortization		68		71		118		135
Impairments				0		0		0
Other expenses	[1]	22		19		38		42
Taxes other than income		0		0		0		0
Net interest and other		0		0		0		0
Income tax provision (benefit)		(2)		27		(14)		24
Segment income (loss) /Loss from continuing operations		55		41		59		64
Capital expenditures	[2]	12		99		44		245
Oil Sands Mining Segment [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues		185		147		333		372
Marketing revenues		13		43		25		43
Total revenues		198		190		358		415
Income from equity method investments		0		0		0		0
Net gain ( loss) on disposal of assets and other income		1		0		1		1
Production expenses		165		207		306		382
Marketing costs		13		41		25		41
Exploration Expenses		7		0		7		0
Depreciation, depletion and amortization		49		35		109		97
Impairments				0		0		0
Other expenses	[1]	9		9		16		18
Taxes other than income		4		5		9		10
Net interest and other		0		0		0		0
Income tax provision (benefit)		(10)		(30)		(27)		(36)
Segment income (loss) /Loss from continuing operations		(38)		(77)		(86)		(96)
Capital expenditures	[2]	7		16		16		37
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	[3]	(91)		(44)		(114)		(21)
Marketing revenues		0		0		0		0
Total revenues		(91)		(44)		(114)		(21)
Income from equity method investments		0		0		0		0
Net gain ( loss) on disposal of assets and other income		296	[4]	0		233	[5]	1
Production expenses		0		0		0		0
Marketing costs		0		0		0		0
Exploration Expenses		141	[6]	0		141	[6]	0
Depreciation, depletion and amortization		11		11		23		23
Impairments				44	[7]	0		44	[7]
Other expenses		99	[8]	122	[1],[9]	218	[1],[10]	251	[1],[11]
Taxes other than income		0		6		1		7
Net interest and other		86		58		171		105
Income tax provision (benefit)		(15)		20	[12]	(150)		(26)	[12]
Segment income (loss) /Loss from continuing operations		(117)		(305)		(285)		(424)
Capital expenditures	[2]	5		12		8		14
Workforce reduction						8		43
United States and Foreign Pension Plans Defined Benefit [Member]
Segment Reporting Information [Line Items]
Net settlement loss		31		64		79		$ 81	[13]
United States and Foreign Pension Plans Defined Benefit [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net settlement loss	[13]	$ 31		64		$ 79
Alberta Government [Member] | Foreign Tax Authority [Member]
Segment Reporting Information [Line Items]
Deferred Income Tax Expense (Benefit)				135
Deferred Foreign Income Tax Expense (Benefit)				$ 135

[1] Includes other operating expenses and general and administrative expenses.

[2] Includes accruals.

[3] Unrealized loss on commodity derivative instruments.

[4] Primarily related to partial sale of Wyoming upstream and midstream assets. (See note 6.)

[5] Related to net gain on disposal of assets (see Note 6)

[6] Impairments associated with decision to not drill remaining Gulf of Mexico undeveloped leases

[7] Proved property impairments (See Note 13).

[8] Includes pension settlement loss of $31 million (See note 8).

[9] Includes pension settlement loss of $64 million (see Note 8).

[10] Includes pension settlement loss of $79 million and severance related expenses associated with workforce reductions of $8 million (see Note 8)

[11] Includes pension settlement loss of $81 million and severance related expenses associated with workforce reductions of $43 million (see Note 8).

[12] Includes $135 million of deferred tax expense related to Alberta provincial corporate tax rate increase (see Note 9)

[13] Settlements are recognized as they occur, once it is probable that lump sum payments from a plan for a given year will exceed the plan's total service and interest cost for that year.