- Summary of Future Minimum Lease Payments Under Non-Cancelable Capital and Operating Leases (Details) $ in Millions	Dec. 31, 2015 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating leases due 2016	$ 198
Operating leases due 2017	199
Operating leases due 2018	163
Operating leases due 2019	128
Operating leases due 2020	114
Operating leases due thereafter	498
Operating leases due	1,300
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Capital leases due 2016	58
Capital leases due 2017	57
Capital leases due 2018	53
Capital leases due 2019	46
Capital leases due 2020	45
Capital leases due thereafter	125
Capital leases due	384
Less amount representing interest payments	(98)
Present value of minimum lease payments	286
Total operating and capital leases due 2016	256
Total operating and capital leases due 2017	256
Total operating and capital leases due 2018	216
Total operating and capital leases due 2019	174
Total operating and capital leases due 2020	159
Total operating and capital leases due thereafter	623
Total operating and capital leases due	$ 1,684