Lease Commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Leased Assets [Line Items]
Non-cancelable term of operating and capital leases (in years)	1 year
Schedule of capitalized leased assets
Upstream	$ 433	$ 585
Downstream	316	316
All Other	0	0
Total	749	901
Less: Accumulated amortization	479	568
Net capitalized leased assets	270	333
Rental expenses incurred for operating leases
Minimum rentals	973	892	931
Contingent rentals	7	11	10
Total	980	903	941
Less: Sublease rental income	32	39	41
Net rental expense	948	864	900
Estimated future minimum lease payments (net of noncancelable sublease rentals) under operating and capital leases
Operating Leases, 2013	727
Capital Leases, 2013	45
Operating Leases, 2014	657
Capital Leases, 2014	37
Operating Leases, 2015	618
Capital Leases, 2015	23
Operating Leases, 2016	528
Capital Leases, 2016	13
Operating Leases, 2017	401
Capital Leases, 2017	12
Operating Leases, Thereafter	617
Capital Leases, Thereafter	59
Operating Leases, Totol	3,548
Capital Leases, Total	189
Less: Amounts representing interest and executory costs	(40)
Net present values	149
Less: Capital lease obligations included in short-term debt	(50)
Long-term capital lease obligations	$ 99	$ 128
Maximum [Member]
Operating Leased Assets [Line Items]
Contingent rentals, renewal option term (in years)	25 years