Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Taxes (Textual) [Abstract]
Income tax provision	$ 19	$ 22	$ 49	$ 52
Effective tax rate	17.40%	17.50%	17.60%	17.70%
Likelihood of uncertain tax positions			greater than 50%
Unrecognized tax benefits	$ 42		$ 42
Interest accrued for unrecognized tax benefits (less than $1 million)	$ 1		$ 1