Intangible Assets Including Goodwill - Intangible Assets by Class (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Intangible asset balances by major asset class:
Gross Carrying Amount	$ 7,633	$ 8,466
Accumulated Amortization	(3,652)	(3,778)
Net Carrying Amount	3,981	4,688
Capitalized software
Intangible asset balances by major asset class:
Gross Carrying Amount	1,586	1,537
Accumulated Amortization	(750)	(661)
Net Carrying Amount	835	876
Client relationships
Intangible asset balances by major asset class:
Gross Carrying Amount	2,416	2,831
Accumulated Amortization	(1,054)	(1,228)
Net Carrying Amount	1,363	1,602
Completed technology
Intangible asset balances by major asset class:
Gross Carrying Amount	2,872	3,322
Accumulated Amortization	(1,562)	(1,668)
Net Carrying Amount	1,310	1,654
Patents/trademarks
Intangible asset balances by major asset class:
Gross Carrying Amount	707	730
Accumulated Amortization	(267)	(205)
Net Carrying Amount	440	525
Other intangible assets
Intangible asset balances by major asset class:
Gross Carrying Amount	52	46
Accumulated Amortization	(19)	(15)
Net Carrying Amount	$ 32	$ 31