Goodwill and Intangible Assets Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Intangible Assets:
Gross Carrying Amount	$ 3,348	$ 3,415
Accumulated Amortization	(2,784)	(2,474)
Intangible assets, net	564	941
Aggregate amortization expense for intangible assets	376	424	433
Future intangible asset amortization
2015	306
2016	182
2017	50
2018	22
2019	4
Thereafter	0
Intangible assets, net	564	941
Customer Lists [Member]
Intangible Assets:
Gross Carrying Amount	1,641	1,653
Accumulated Amortization	(1,367)	(1,213)
Intangible assets, net	274	440
Weighted-Average Useful Life (Years)	5 years	5 years
Future intangible asset amortization
Intangible assets, net	274	440
Trademarks and Trade Names [Member]
Intangible Assets:
Gross Carrying Amount	849	780
Accumulated Amortization	(729)	(677)
Intangible assets, net	120	103
Weighted-Average Useful Life (Years)	5 years	5 years
Future intangible asset amortization
Intangible assets, net	120	103
Developed Technology
Intangible Assets:
Gross Carrying Amount	579	554
Accumulated Amortization	(478)	(401)
Intangible assets, net	101	153
Weighted-Average Useful Life (Years)	4 years	4 years
Future intangible asset amortization
Intangible assets, net	101	153
Other Intangible Assets [Member]
Intangible Assets:
Gross Carrying Amount	279	273
Accumulated Amortization	(210)	(183)
Intangible assets, net	69	90
Weighted-Average Useful Life (Years)	4 years	4 years
Future intangible asset amortization
Intangible assets, net	$ 69	$ 90