Intangible Assets - Schedule of Intangible Assets by Class (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,010	$ 3,967
Accumulated Amortization	2,177	2,085
Net Book Value	1,833	1,882
Customer related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,293	2,293
Accumulated Amortization	1,229	1,168
Net Book Value	1,064	1,125
Acquired software and technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	578	579
Accumulated Amortization	475	460
Net Book Value	103	119
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	117	117
Accumulated Amortization	68	64
Net Book Value	49	53
Capitalized software development costs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	761	737
Accumulated Amortization	292	282
Net Book Value	469	455
Purchased software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	261	241
Accumulated Amortization	113	111
Net Book Value	$ 148	$ 130