Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
Capital lease agreement period	3 years
Capital Leases, Future Minimum Payments Due
2016	$ 16
2017	15
2018	16
2019	16
2020	17
Thereafter	94
Total minimum lease payments	174
Less: amount representing interest and taxes	(60)
Less: current portion of the present value of minimum lease payments	(7)	$ (114)
Capital lease obligations, less current portion	107	119
Operating Leases, Future Minimum Payments Due
2016	209
2017	230
2018	216
2019	200
2020	159
Thereafter	438
Total minimum lease payments	1,452
Financing Obligation, Future Minimum Payments Due
2016	0
2017	0
2018	0
2019	13
2020	25
Thereafter	299
Total minimum lease payments	337
Financing obligation, building in progress - leased facility	62
Operating lease expense	181	$ 125	$ 130
Other contractual commitments
Other contractual commitments	$ 1,220
Contractual obligation, period	5 years
Minimum
Leases [Abstract]
Interest rate	1.00%
Lease expiration year	2016
Maximum
Leases [Abstract]
Interest rate	13.00%
Lease expiration year	2032
Building
Leases [Abstract]
Capital lease agreement period	15 years