Goodwill and Intangible Assets Weighted-average useful lives assigned to finite-lived intangible assets acquired in business combinations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 464	$ 82
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years	12 years
Customer-Related Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	314	55
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years	12 years
Trademarks and Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	148	27
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years	12 years
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 2	$ 0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years