Long-Term Debt and Shareholders' Equity (Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,893	$ 7,463
OCI before reclassifications, net of tax	155	(1,256)
Amounts reclassified from AOCI, net of tax	37	(10)
Total other comprehensive income (loss), net of tax	192	(1,266)
Balance at end of period	5,184	6,294
Income tax (benefit) expense included in other comprehensive income (loss)	63	(410)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(3,112)	(80)
Balance at end of period	(2,920)	(1,346)
Net unrealized gains/(losses) on investment securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(2,800)	(78)
OCI before reclassifications, net of tax	126	(1,121)
Amounts reclassified from AOCI, net of tax	0	0
Total other comprehensive income (loss), net of tax	126	(1,121)
Balance at end of period	(2,674)	(1,199)
Income tax (benefit) expense included in other comprehensive income (loss)	41	(363)
Net unrealized gains/(losses) on derivatives and other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(311)	0
OCI before reclassifications, net of tax	29	(135)
Amounts reclassified from AOCI, net of tax	37	(10)
Total other comprehensive income (loss), net of tax	66	(145)
Balance at end of period	(245)	(145)
Income tax (benefit) expense included in other comprehensive income (loss)	22	(47)
Pension and post-retirement
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1)	(2)
OCI before reclassifications, net of tax	0	0
Amounts reclassified from AOCI, net of tax	0	0
Total other comprehensive income (loss), net of tax	0	0
Balance at end of period	(1)	(2)
Income tax (benefit) expense included in other comprehensive income (loss)	$ 0	$ 0