Income Taxes (Unaudited) (Details 1) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2017
Income Tax Contingency [Line Items]
Income Tax Expense (Benefit)	$ 120	$ 220
Effective income tax rate	17.80%	31.30%
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 175
Maximum | Scenario, Forecast [Member]
Income Tax Contingency [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions			$ (45)