Derivatives Derivatives (Schedule of Cash Flow Hedges Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Deferred Gain on Interest Rate Cash Flow Hedges	$ 39
Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Cash Flow Hedges Derivative Instruments at Fair Value, Net	60	$ 0	$ 0
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	64	0
Reclassification from Other Comprehensive Income	$ (4)	$ 0