Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Definite-lived intangible assets
Carrying amount of indefinite-lived intangible assets	$ 644	$ 630
Carrying amount of indefinite-lived intangible assets	67
Amount of indefinite-lived intangible assets acquired	14
Gross Carrying Amount	531	534
Accumulated Amortization	(398)	(375)
Net Carrying Amount	133	159
Definite-lived intangible assets acquired during the year, amount assigned	$ 9
Definite-lived intangible assets acquired during the year, weighted-average amortization period	5 years
Aggregate amortization expense for definite-lived intangible assets	$ 33	40	$ 45
Estimated intangible amortization expense for next five years:
2016	26
2017	22
2018	21
2019	18
2020	13
Customer relationships [Member]
Definite-lived intangible assets
Gross Carrying Amount	149	150
Accumulated Amortization	(106)	(97)
Net Carrying Amount	43	53
Contracts [Member]
Definite-lived intangible assets
Gross Carrying Amount	233	233
Accumulated Amortization	(189)	(180)
Net Carrying Amount	44	53
Other [Member]
Definite-lived intangible assets
Gross Carrying Amount	149	151
Accumulated Amortization	(103)	(98)
Net Carrying Amount	$ 46	$ 53