Intangible Assets Including Goodwill - Intangible Assets by Class (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Intangible asset balances by major asset class
Gross Carrying Amount	$ 6,410	$ 6,489
Accumulated Amortization	(3,454)	(3,402)
Net Carrying Amount	2,956	3,087
Capitalized software
Intangible asset balances by major asset class
Gross Carrying Amount	1,665	1,568
Accumulated Amortization	(683)	(629)
Net Carrying Amount	982	939
Client relationships
Intangible asset balances by major asset class
Gross Carrying Amount	2,022	2,068
Accumulated Amortization	(1,150)	(1,123)
Net Carrying Amount	872	945
Completed technology
Intangible asset balances by major asset class
Gross Carrying Amount	2,032	2,156
Accumulated Amortization	(1,248)	(1,296)
Net Carrying Amount	784	860
Patents/trademarks
Intangible asset balances by major asset class
Gross Carrying Amount	635	641
Accumulated Amortization	(348)	(330)
Net Carrying Amount	287	311
Other intangible assets
Intangible asset balances by major asset class
Gross Carrying Amount	56	56
Accumulated Amortization	(25)	(23)
Net Carrying Amount	$ 30	$ 32