Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intangible Assets:
Gross Carrying Amount	$ 1,408	$ 1,457
Accumulated Amortization	(1,318)	(1,324)
Intangible assets, net	90	133
Aggregate amortization expense for intangible assets	66	120	$ 175
Customer lists and user base
Intangible Assets:
Gross Carrying Amount	419	434
Accumulated Amortization	(399)	(407)
Intangible assets, net	$ 20	$ 27
Weighted Average Useful Life (Years)	5 years	5 years
Marketing related
Intangible Assets:
Gross Carrying Amount	$ 594	$ 642
Accumulated Amortization	(570)	(596)
Intangible assets, net	$ 24	$ 46
Weighted Average Useful Life (Years)	5 years	5 years
Developed technologies
Intangible Assets:
Gross Carrying Amount	$ 238	$ 237
Accumulated Amortization	(215)	(195)
Intangible assets, net	$ 23	$ 42
Weighted Average Useful Life (Years)	4 years	4 years
All other
Intangible Assets:
Gross Carrying Amount	$ 157	$ 144
Accumulated Amortization	(134)	(126)
Intangible assets, net	$ 23	$ 18
Weighted Average Useful Life (Years)	4 years	4 years