Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	31.50%	32.10%
Unrecognized tax benefits	$ 120		$ 120
Accrued interest and penalties associated with uncertain tax positions	$ 34		$ 31