Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate (as a percent)	29.50%	31.50%
Unrecognized tax benefits	$ 156		$ 161
Accrued interest and penalties associated with uncertain tax positions	$ 46		$ 44