Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Leases [Abstract]
Capital lease agreement period	3 years
Operating lease expense	$ 29	$ 41
Minimum
Leases [Abstract]
Interest rate	1.00%
Expiration date of lease	2014
Maximum
Leases [Abstract]
Interest rate	13.00%
Expiration date of lease	2029
Buildings
Leases [Abstract]
Capital lease agreement period	15 years