Derivative Instruments and Hedging Activities (Fair Value Of Derivatives Designated As Hedging Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Interest Rate Derivative Assets, at Fair Value	$ 33
Interest Rate Derivative Liabilities, at Fair Value	0
Designated As Hedging Instrument [Member]
Derivative [Line Items]
Interest Rate Derivative Assets, at Fair Value	33	$ 19
Interest Rate Derivative Liabilities, at Fair Value		0
Derivative Instruments in Hedges, Assets, at Fair Value	33	19
Derivative Instruments in Hedges, Liabilities, at Fair Value	$ 0	$ 0