Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	29.50%	25.90%	30.60%	30.70%
Unrecognized tax benefits	$ 121		$ 121		$ 120
Accrued interest and penalties associated with uncertain tax positions	$ 40		$ 40		$ 31