Business Segment Information - Financial Segment Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Oil and gas production revenues	$ 16,947	$ 16,810	$ 12,183
Depreciation, depletion, and amortization
Recurring	5,183	4,095	3,083
Additional	1,926	109
Asset retirement obligation accretion	232	154	111
Lease operating expenses	2,968	2,605	2,032
Gathering and transportation	303	296	178
Taxes other than income	862	899	690
Operating Income (Loss)	5,473	8,652	6,089
Other Income (Expense):
Other	131	78	(91)
General and administrative	(531)	(459)	(380)
Merger, acquisitions & transition	(31)	(20)	(183)
Financing costs, net	(165)	(158)	(229)
INCOME BEFORE INCOME TAXES	4,877	8,093	5,206
Net Property and Equipment	53,280	45,448	38,151
Total Assets	60,737	52,051	43,425
Additions to Net Property and Equipment	14,955	11,919	19,056
United States [Member]
Segment Reporting Information [Line Items]
Oil and gas production revenues	6,226	6,103	4,300
Depreciation, depletion, and amortization
Recurring	2,056	1,684	1,163
Asset retirement obligation accretion	112	97	62
Lease operating expenses	1,386	1,167	924
Gathering and transportation	69	64	42
Taxes other than income	292	259	190
Operating Income (Loss)	2,311	2,832	1,919
Other Income (Expense):
Net Property and Equipment	28,552	21,038	19,069
Total Assets	31,175	23,499	21,326
Additions to Net Property and Equipment	9,586	3,854	10,371
Canada [Member]
Segment Reporting Information [Line Items]
Oil and gas production revenues	1,322	1,617	1,074
Depreciation, depletion, and amortization
Recurring	594	546	294
Additional	1,883
Asset retirement obligation accretion	41	26	23
Lease operating expenses	458	470	334
Gathering and transportation	163	165	75
Taxes other than income	50	51	35
Operating Income (Loss)	(1,867)	359	313
Other Income (Expense):
Net Property and Equipment	6,640	8,022	7,497
Total Assets	7,142	8,816	8,273
Additions to Net Property and Equipment	1,096	1,288	5,277
Egypt [Member]
Segment Reporting Information [Line Items]
Oil and gas production revenues	4,554	4,791	3,372
Depreciation, depletion, and amortization
Recurring	925	818	754
Lease operating expenses	410	398	298
Gathering and transportation	39	35	31
Taxes other than income	14	13	10
Operating Income (Loss)	3,166	3,527	2,279
Other Income (Expense):
Net Property and Equipment	5,151	4,923	4,726
Total Assets	7,311	6,656	6,036
Additions to Net Property and Equipment	1,153	1,015	1,569
Australia [Member]
Segment Reporting Information [Line Items]
Oil and gas production revenues	1,575	1,734	1,459
Depreciation, depletion, and amortization
Recurring	466	440	408
Asset retirement obligation accretion	17	10	9
Lease operating expenses	215	197	185
Taxes other than income	11	9	11
Operating Income (Loss)	866	1,078	846
Other Income (Expense):
Net Property and Equipment	5,312	4,194	3,495
Total Assets	6,280	4,681	3,831
Additions to Net Property and Equipment	1,581	1,140	925
North Sea [Member]
Segment Reporting Information [Line Items]
Oil and gas production revenues	2,751	2,091	1,606
Depreciation, depletion, and amortization
Recurring	914	409	304
Asset retirement obligation accretion	58	17	15
Lease operating expenses	315	208	168
Gathering and transportation	24	25	25
Taxes other than income	451	539	422
Operating Income (Loss)	989	893	672
Other Income (Expense):
Net Property and Equipment	5,927	5,737	1,970
Total Assets	6,874	6,600	2,362
Additions to Net Property and Equipment	1,104	4,175	620
Argentina [Member]
Segment Reporting Information [Line Items]
Oil and gas production revenues	519	474	372
Depreciation, depletion, and amortization
Recurring	228	198	160
Asset retirement obligation accretion	4	4	2
Lease operating expenses	184	165	123
Gathering and transportation	8	7	5
Taxes other than income	44	28	22
Operating Income (Loss)	51	72	60
Other Income (Expense):
Net Property and Equipment	1,621	1,512	1,336
Total Assets	1,835	1,766	1,537
Additions to Net Property and Equipment	337	374	274
Other International [Member]
Depreciation, depletion, and amortization
Additional	43	109
Operating Income (Loss)	(43)	(109)
Other Income (Expense):
Net Property and Equipment	77	22	58
Total Assets	120	33	60
Additions to Net Property and Equipment	$ 98	$ 73	$ 20