Long-Term Debt And Shareholders' Equity (Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ 43
Other comprehensive income	$ 96	$ 147	312	$ 275
Ending balance	355		355
Net unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			29	(228)
OCI before reclassifications, net of tax			241	237
Amounts reclassified from AOCI, net of tax			0	0
Other comprehensive income			241	237
Ending balance	270	9	270	9
Net unrealized gains (losses) on investment securities, tax			79	78
Net unrealized gains (losses) on derivatives and other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			28	(1)
OCI before reclassifications, net of tax			71	36
Amounts reclassified from AOCI, net of tax			(13)	2
Other comprehensive income			58	38
Ending balance	86	37	86	37
Net unrealized gains (losses) on derivatives and other			19	12
Pension and post-retirement
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(14)	(21)
OCI before reclassifications, net of tax			13	0
Amounts reclassified from AOCI, net of tax			0	0
Other comprehensive income			13	0
Ending balance	(1)	(21)	(1)	(21)
Pension and post-retirement, tax			4	0
Total
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			43	(250)
OCI before reclassifications, net of tax			325	273
Amounts reclassified from AOCI, net of tax			(13)	2
Other comprehensive income	96	147	312	275
Ending balance	$ 355	$ 25	355	25
Other Comprehensive Income (Loss), Tax			$ 102	$ 90