Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Investment securities, Balance at beginning of period, net of tax	$ 150	$ 129
Investment securities, Net unrealized holding gains (losses) arising during the period	(242)	63
Investment securities, Provision (benefit) for income taxes	(89)	23
Investment securities, Net unrealized holding gains (losses) arising during period, net of tax	(153)	40
Investment securities, Net realized gains included in net securities (losses) gains	0	11
Investment securities, Provision for income taxes	0	4
Investment securities, Reclassification adjustment for net securities (losses) gains included in net income, net of tax	0	7
Investment securities, Change in net unrealized gains (losses) on investment securities available-for-sale, net of tax	(153)	33
Investment securities, Balance at end of period, net of tax	(3)	162
Benefit plans, Balance at beginning of period, net of tax	(563)	(485)
Benefit plans, Net defined benefit pension and other postretirement adjustment arising during the period, net of tax	0	0
Less: Amortization of actuarial net loss	(44)	(31)
Less: Amortization of prior service cost	(1)	(1)
Less: Amortization of transition obligation	0	(2)
Benefit plans, Amounts recognized in emoloyee benefits	(45)	(34)
Benefit plans, Benefit for income taxes	(17)	(12)
Benefit plans, Adjustment for amounts recognized as components of net periodic benefit cost during the period, net of tax	(28)	(22)
Benefit plans, Change in defined benefit pension and other postretirement plans adjustment, net of tax	28	22
Benefit plans, Balance at end of period, net of tax	(535)	(463)
Total accumulated other comprehensive loss at end of period, net of tax	$ (538)	$ (301)	$ (413)