Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Jan. 01, 2017
Income Tax Disclosure [Abstract]
Tax expense	$ 70	$ 78
Income before income taxes	239	267
Favorable impact on income tax expense, other reconciling items	$ 2	12
Favorable impact on income tax expense, release of valuation allowance		7
Favorable impact on income tax expense, other discrete tax adjustments		$ 5
Unrecognized tax benefits			$ 63
Favorable impact on income tax expense, if unrecognized tax benefits were recognized			47
Accrued interest			4
Unrecognized tax benefits requiring the use of cash if not favorably settled			$ 12