Property and Equipment, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Gross Amount	$ 847	$ 843
Accumulated Depreciation and Amortization	(611)	(598)
Net Amount	236	245
Depreciation and amortization excluding intangible amortization	81	78	$ 89
Leases [Abstract]
Sale Leaseback Transaction, Net Proceeds, Financing Activities		56
Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months	4
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years	4
Minimum Lease Payments, Sale Leaseback Transactions, within Three Years	5
Minimum Lease Payments, Sale Leaseback Transactions, within Four Years	5
Minimum Lease Payments, Sale Leaseback Transactions, within Five Years	5
Minimum Lease Payments, Sale Leaseback Transactions, Thereafter	19
Minimum Lease Payments, Sale Leaseback Transactions	42
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Next Twelve Months	(3)
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years	(3)
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years	(3)
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Four Years	(3)
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Five Years	(3)
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Thereafter	(6)
Future Minimum Sublease Rentals, Sale Leaseback Transactions	(21)
Software and Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	490	487
Accumulated Depreciation and Amortization	(388)	(391)
Net Amount	102	96
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	116	114
Accumulated Depreciation and Amortization	(91)	(84)
Net Amount	25	30
Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	127	102
Accumulated Depreciation and Amortization	(84)	(76)
Net Amount	43	26
Building [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	72	72
Accumulated Depreciation and Amortization	(28)	(26)
Net Amount	44	46
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	22	23
Accumulated Depreciation and Amortization	(20)	(21)
Net Amount	2	2
Land [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	3	3
Accumulated Depreciation and Amortization	0	0
Net Amount	3	3
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Gross Amount	17	42
Accumulated Depreciation and Amortization	0	0
Net Amount	17	42
Capitalized internally developed software, balance	22	19
Software Development [Member]
Property, Plant and Equipment [Line Items]
Capitalized internally developed software costs	42	27	24
Depreciation and amortization excluding intangible amortization	$ 41	$ 47	$ 57