Income Taxes (Schedule Of Tax Effects Of Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net unrealized gains (losses) on investments:
Unrealized holding gain (loss) arising during the period	$ (1)		$ 6
Less: reclassification adjustment for amounts included in net income	3		(1)
Equity investee's unrealized gain on investments	1
Unamortized losses and prior service costs for postretirement benefit plans:
Adjustments arising during the period	(100)	(30)	(58)
Less: amortization of losses and prior service costs included in net income	33	35	26
Equity investee's defined benefit plan adjustments	2	(9)	(1)
Net unrealized gains (losses) on designated hedges:
Unrealized holding gain (loss) arising during the period	20	18	(6)
Less: reclassification adjustment for amounts included in net income	7	(21)	(9)
Income tax benefit related to items of other comprehensive income	$ (35)	$ (7)	$ (43)