Goodwill and Other Intangible Assets (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Definite-lived intangible assets
Carrying amount of indefinite-lived intangible assets	$ 630	$ 631
Carrying amount of indefinite-lived intangible assets	67	67
Gross Carrying Amount	534	547
Accumulated Amortization	(375)	(348)
Net Carrying Amount	159	199
Definite-lived intangible assets acquired during the year, amount assigned	3
Definite-lived intangible assets acquired during the year, weighted-average amortization period	5 years
Increase (decrease) to net definite-lived intangible assets due to changes in foreign currency exchange rates	(3)	1	4
Aggregate amortization expense for definite-lived intangible assets	40	45	47
Estimated intangible amortization expense for next five years:
2015	32
2016	26
2017	22
2018	20
2019	17
Customer relationships [Member]
Definite-lived intangible assets
Gross Carrying Amount	150	152
Accumulated Amortization	(97)	(87)
Net Carrying Amount	53	65
Contracts [Member]
Definite-lived intangible assets
Gross Carrying Amount	233	240
Accumulated Amortization	(180)	(167)
Net Carrying Amount	53	73
Other [Member]
Definite-lived intangible assets
Gross Carrying Amount	151	155
Accumulated Amortization	(98)	(94)
Net Carrying Amount	$ 53	$ 61