Derivative Instruments (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Nov. 21, 2016	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Class of Warrant or Right, Unissued	1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	84,500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 6.43
Warrants and Rights Outstanding	$ 172	$ 156
Fair Value Adjustment of Warrants		16
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Debt Instrument, Unamortized Premium		7		$ 23
Deferred (Gain) Loss on Discontinuation of Fair Value Hedge		(9)		(10)
Foreign currency forward contracts [Member]
Derivative [Line Items]
Notional amount		$ 1,600		$ 1,700
Additional Paid-in Capital [Member]
Derivative [Line Items]
Stock Issued During Period, Shares, New Issues	84,500,000		115,000,000