Goodwill and Acquired Intangible Assets Intangible Assets Reclassified as Held for Sale (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	$ 1,277	$ 1,279
Accumulated Amortization	(481)	(436)
Total	796	843
Total Indefinite-Lived Intangible Assets, Net Amount	1,295	1,251
Total Intangible Assets, Gross Amount	2,572	2,530
Total Intangible Assets, Net Amount	2,091	2,094
Technology
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	51	38
Accumulated Amortization	(20)	(24)
Total	31	14
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	1,330	1,394
Accumulated Amortization	(502)	(464)
Total	828	930
Other
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	4	7
Accumulated Amortization	(3)	(6)
Total	1	$ 1
Disposal Group, Held-for-sale, Not Discontinued Operations
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	56
Accumulated Amortization	(18)
Total	38
Total Indefinite-Lived Intangible Assets, Net Amount	3
Total Intangible Assets, Gross Amount	59
Total Intangible Assets, Net Amount	41
Disposal Group, Held-for-sale, Not Discontinued Operations | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	54
Accumulated Amortization	(17)
Total	37
Disposal Group, Held-for-sale, Not Discontinued Operations | Other
Finite-Lived Intangible Assets [Line Items]
Total Finite-Lived Intangible Assets, Gross Amount	2
Accumulated Amortization	(1)
Total	$ 1