Long-Term Debt and Shareholders' Equity (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans	$ 865	$ 726
Less: Income tax expense (benefit)	50	78
Net income	153	204
Net unrealized gains/(losses) on investment securities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans	(61)	(65)
Less: Income tax expense (benefit)	(15)	(16)
Net income	(46)	(49)
Net unrealized gains/(losses) on derivatives and other | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans	(34)	(49)
Less: Income tax expense (benefit)	(8)	(12)
Net income	$ (26)	$ (37)