Acquisitions, Goodwill, and Acquired Intangible Assets Goodwill (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Jun. 30, 2015	Sep. 30, 2015
Goodwill [Line Items]
Disclosure of Change of Date for Annual Goodwill Impairment Test		During the second quarter of 2015, we changed the measurement date of our annual goodwill impairment test from October 1 to April 1. This change was not material to our consolidated financial statements as it did not result in the delay, acceleration, or avoidance of an impairment charge. We believe this timing better aligns the goodwill impairment test with our strategic business planning process, which is a key component of the goodwill impairment test. We completed the required annual testing of goodwill for impairment for all reporting units as of April 1, 2015 and determined that goodwill is not impaired.
Goodwill - January 1, 2015			$ 3,319
New acquisitions			239
Other adjustments	[1]		(29)
Goodwill - September 30, 2015			3,529
North America
Goodwill [Line Items]
Goodwill - January 1, 2015			1,978
New acquisitions			41
Other adjustments	[1]		(5)
Goodwill - September 30, 2015			2,014
International
Goodwill [Line Items]
Goodwill - January 1, 2015			735
New acquisitions			17
Other adjustments	[1]		(22)
Goodwill - September 30, 2015			730
AWS
Goodwill [Line Items]
Goodwill - January 1, 2015			606
New acquisitions			181
Other adjustments	[1]		(2)
Goodwill - September 30, 2015			$ 785

[1] Primarily includes changes in foreign exchange rates.