Goodwill and Other Intangible Assets - Schedule of other intangible assets by asset class (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,013	$ 3,397
Accumulated Amortization and Impairment	2,280	1,507
Net Carrying Amount	1,733	1,890
Customer related and contract based
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,550	2,023
Accumulated Amortization and Impairment	1,415	1,198
Net Carrying Amount	1,135	825
Tradenames
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,047	1,027
Accumulated Amortization and Impairment	533	7
Net Carrying Amount	514	1,020
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	416	347
Accumulated Amortization and Impairment	332	302
Net Carrying Amount	$ 84	45
Reclassified gross carrying amount of finite lived intangibles		29
Reclassified accumulated amortization of finite lived intangibles		$ 7