Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Intangible Assets:
Gross Carrying Amount	$ 2,468		$ 2,468		$ 2,459
Accumulated Amortization	(2,185)		(2,185)		(2,154)
Intangible Assets, Net	283		283		305
Amortization expense	43	$ 59	81	$ 124
Customer lists and user base
Intangible Assets:
Gross Carrying Amount	954		954		954
Accumulated Amortization	(888)		(888)		(884)
Intangible Assets, Net	66		$ 66		$ 70
Weighted Average Useful Life (Years)			6 years		6 years
Marketing related
Intangible Assets:
Gross Carrying Amount	789		$ 789		$ 823
Accumulated Amortization	(711)		(711)		(713)
Intangible Assets, Net	78		$ 78		$ 110
Weighted Average Useful Life (Years)			5 years		5 years
Developed technologies
Intangible Assets:
Gross Carrying Amount	445		$ 445		$ 404
Accumulated Amortization	(365)		(365)		(348)
Intangible Assets, Net	80		$ 80		$ 56
Weighted Average Useful Life (Years)			3 years		3 years
All other
Intangible Assets:
Gross Carrying Amount	280		$ 280		$ 278
Accumulated Amortization	(221)		(221)		(209)
Intangible Assets, Net	$ 59		$ 59		$ 69
Weighted Average Useful Life (Years)			4 years		4 years