Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues:
Customer	$ 3,718	$ 3,680	$ 7,495	$ 7,336
Related parties	13	14	27	29
Income from equity method investments,segment	60	120	138	237
Depreciation, depletion and amortization, segment	580	564	1,154	1,199
Income tax provision, segment	1,025	617	1,952	1,153
Exploration and Production Segment [Member]
Revenues:
Customer	3,383	3,220	6,781	6,506
Intersegment revenues		15		41
Related parties	13	14	27	29
Segment revenues, total	3,396	3,249	6,808	6,576
Elimination of intersegment revenues		(15)		(41)
Total revenue	3,396	3,234	6,808	6,535
Segment income	417	601	894	1,269
Income from equity method investments,segment	38	66	102	124
Depreciation, depletion and amortization, segment	521	501	1,037	1,087
Income tax provision, segment	1,110	598	2,146	1,211
Capital expenditures, segment	1,184	749	2,185	1,417
Oil Sands Mining Segment [Member]
Revenues:
Customer	335	447	714	753
Segment revenues, total	335	447	714	753
Total revenue	335	447	714	753
Segment income	51	69	92	101
Depreciation, depletion and amortization, segment	50	49	99	86
Income tax provision, segment	17	23	31	33
Capital expenditures, segment	43	80	95	200
Integrated Gas Segment [Member]
Revenues:
Customer		13		77
Segment revenues, total		13		77
Total revenue		13		77
Segment income	13	43	17	103
Income from equity method investments,segment	22	54	36	113
Depreciation, depletion and amortization, segment		1		3
Income tax provision, segment	5	17	6	43
Capital expenditures, segment	1		1	1
Total All Segments [Member]
Revenues:
Customer	3,718	3,680	7,495	7,336
Intersegment revenues		15		41
Related parties	13	14	27	29
Segment revenues, total	3,731	3,709	7,522	7,406
Elimination of intersegment revenues		(15)		(41)
Total revenue	3,731	3,694	7,522	7,365
Segment income	481	713	1,003	1,473
Income from equity method investments,segment	60	120	138	237
Depreciation, depletion and amortization, segment	571	551	1,136	1,176
Income tax provision, segment	1,132	638	2,183	1,287
Capital expenditures, segment	$ 1,228	$ 829	$ 2,281	$ 1,618