Long-Term Debt and Shareholders' Equity (Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 5,691	$ 4,893
Other comprehensive income (loss) before reclassifications, net of tax	11	106
Amounts reclassified from AOCI, net of tax	72	86
Other comprehensive income, net of tax	83	192
Balance at end of period	5,829	5,184
Income tax expense included in OCI	27	63
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(2,692)	(3,112)
Balance at end of period	(2,609)	(2,920)
Net unrealized gains/(losses) on investment securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(2,526)	(2,800)
Other comprehensive income (loss) before reclassifications, net of tax	12	77
Amounts reclassified from AOCI, net of tax	46	49
Other comprehensive income, net of tax	58	126
Balance at end of period	(2,468)	(2,674)
Income tax expense included in OCI	19	41
Net unrealized gains/(losses) on derivatives and other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(165)	(311)
Other comprehensive income (loss) before reclassifications, net of tax	(1)	29
Amounts reclassified from AOCI, net of tax	26	37
Other comprehensive income, net of tax	25	66
Balance at end of period	(140)	(245)
Income tax expense included in OCI	8	22
Pension and post-retirement
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1)	(1)
Other comprehensive income (loss) before reclassifications, net of tax	0	0
Amounts reclassified from AOCI, net of tax	0	0
Other comprehensive income, net of tax	0	0
Balance at end of period	(1)	(1)
Income tax expense included in OCI	$ 0	$ 0