Supplemental Oil and Gas Disclosures (Unaudited) - Revenue and Direct Cost Information Relating to Company's Oil and Gas Exploration and Production Activities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Oil and gas production revenues	$ 5,367	$ 6,510	[1]	$ 12,795	[1]
Depreciation, depletion, and amortization	2,460	2,976		4,195
Asset retirement obligation accretion	156	145	[1],[2]	154	[1],[2]
Lease operating expenses	1,494	1,854	[1]	2,238	[1]
Gathering and transportation	200	211	[1]	273	[1]
Exploration expenses	473	2,771		2,499
Impairments related to oil and gas properties	427	7,389		6,068
Production taxes	120	259		546
Income tax	148	(3,049)		(1,070)
Oil and gas properties production expense	5,478	12,556		14,903
Results of operation	(111)	(6,046)		(2,108)
United States [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Oil and gas production revenues	1,997	2,637		5,744
Depreciation, depletion, and amortization	1,055	1,455		2,294
Asset retirement obligation accretion	34	28		43
Lease operating expenses	553	739		921
Gathering and transportation	80	68		93
Exploration expenses	285	2,145		2,113
Impairments related to oil and gas properties	61	6,154		2,372
Production taxes	135	178		342
Income tax	(72)	(2,886)		(864)
Oil and gas properties production expense	2,131	7,881		7,314
Results of operation	(134)	(5,244)		(1,570)
Canada [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Oil and gas production revenues	343	498		1,092
Depreciation, depletion, and amortization	174	251		382
Asset retirement obligation accretion	47	43		39
Lease operating expenses	181	244		384
Gathering and transportation	68	89		123
Exploration expenses	88	231		162
Impairments related to oil and gas properties	366	1,031		1,645
Production taxes	18	23		27
Income tax	(162)	(369)		(421)
Oil and gas properties production expense	780	1,543		2,341
Results of operation	(437)	(1,045)		(1,249)
Egypt [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Oil and gas production revenues	2,057	2,095		3,643
Depreciation, depletion, and amortization	733	780		735
Lease operating expenses	446	522		499
Gathering and transportation	44	45		40
Exploration expenses	48	154		112
Impairments related to oil and gas properties	0	193		173
Income tax	354	180		938
Oil and gas properties production expense	1,625	1,874		2,497
Results of operation	432	221		1,146
North Sea [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Oil and gas production revenues	970	1,280		2,316
Depreciation, depletion, and amortization	498	490		784
Asset retirement obligation accretion	75	74		72
Lease operating expenses	314	349		434
Gathering and transportation	8	9		17
Exploration expenses	37	237		119
Impairments related to oil and gas properties	0	11		1,878
Production taxes	(33)	58		177
Income tax	28	26		(723)
Oil and gas properties production expense	927	1,254		2,758
Results of operation	43	26		(442)
Other International [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Exploration expenses	15	4		(7)
Oil and gas properties production expense	15	4		(7)
Results of operation	$ (15)	$ (4)		$ 7

[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.