Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	30.10%		30.60%
Income tax benefit, including reversal of interest and penalties		$ (107)
Liability for tax-related interest and penalties				$ 181