Lease Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Leased Assets [Line Items]
Non-cancelable term of operating and capital leases (in years)	1 year
Schedule of capitalized leased assets
Upstream	$ 800	$ 765
Downstream	98	97
All Other	0	0
Total	898	862
Less: Accumulated amortization	448	381
Net capitalized leased assets	450	481
Rental expenses incurred for operating leases
Minimum rentals	1,041	1,080	$ 1,049
Contingent rentals	2	1	1
Total	1,043	1,081	1,050
Less: Sublease rental income	9	14	25
Net rental expense	1,034	1,067	$ 1,025
Estimated future minimum lease payments (net of noncancelable sublease rentals) under operating and capital leases
Operating Leases, 2016	846
Capital Leases, 2016	23
Operating Leases, 2017	689
Capital Leases, 2017	21
Operating Leases, 2018	554
Capital Leases, 2018	19
Operating Leases, 2019	420
Capital Leases, 2019	19
Operating Leases, 2020	311
Capital Leases, 2020	6
Operating Leases, Thereafter	528
Capital Leases, Thereafter	62
Operating Leases, Total	3,348
Capital Leases, Total	150
Less: Amounts representing interest and executory costs	(53)
Net present values	97
Less: Capital lease obligations included in short-term debt	(17)
Long-term capital lease obligations	$ 80	$ 68
Maximum [Member]
Operating Leased Assets [Line Items]
Contingent rentals, renewal option term (in years)	25 years