Income Taxes (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance as of January 1	$ 22us-gaap_UnrecognizedTaxBenefits	$ 16us-gaap_UnrecognizedTaxBenefits	$ 12us-gaap_UnrecognizedTaxBenefits
Tax positions related to the current period:
Gross increase	2	4	2
Gross decrease	0	0	0
Tax positions related to prior periods:
Gross increase	0	2	5
Gross decrease	0	0	0
Settlements	(2)	0	(3)
Lapse of statutes of limitations	0	0	0
Balance as of December 31	$ 22us-gaap_UnrecognizedTaxBenefits	$ 22us-gaap_UnrecognizedTaxBenefits	$ 16us-gaap_UnrecognizedTaxBenefits

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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