Derivative Instruments (Gains (Losses) On Derivative Instruments Designated As Cash Flow Hedges) (Details) - Cash Flow Hedges [Member] - Other Comprehensive Income (Loss) [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	$ 3	$ (3)	$ 10	$ (15)
Offset to interest and debt expense		$ 1	$ 1	$ 3