Acquisitions, Goodwill, and Acquired Intangible Assets Goodwill (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Goodwill [Line Items]
Goodwill - January 1, 2015	$ 3,319
New acquisitions	211
Other adjustments	(39)	[1]
Goodwill - March 31, 2015	3,491
North America
Goodwill [Line Items]
Goodwill - January 1, 2015	1,978
New acquisitions	40
Other adjustments	(3)	[1]
Goodwill - March 31, 2015	2,015
International
Goodwill [Line Items]
Goodwill - January 1, 2015	735
New acquisitions	17
Other adjustments	(36)	[1]
Goodwill - March 31, 2015	716
AWS
Goodwill [Line Items]
Goodwill - January 1, 2015	606
New acquisitions	154
Other adjustments	0	[1]
Goodwill - March 31, 2015	$ 760

[1] Primarily includes changes in foreign exchange rates.