Long-Term Debt and Shareholders' Equity (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans	$ 877	$ 791	$ 1,742	$ 1,517
Less: Income tax expense (benefit)	61	51	111	129
Net income	201	175	354	379
Net unrealized gains/(losses) on investment securities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans	(67)	(72)	(128)	(137)
Less: Income tax expense (benefit)	(17)	(18)	(32)	(34)
Net income	(50)	(54)	(96)	(103)
Net unrealized gains/(losses) on derivatives and other | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans	(31)	(40)	(65)	(89)
Less: Income tax expense (benefit)	(8)	(10)	(16)	(22)
Net income	$ (23)	$ (30)	$ (49)	$ (67)