Shareholders' Equity (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated other comprehensive income [Line Items]
Securities gains (losses), net									$ 4	$ (15)	$ 71
Interest and fees on loans									3,196	2,112	1,935
Less: Income tax expense (benefit)									206	245	317
Net income	$ 126	$ 175	$ 175	$ 204	$ 284	$ 217	$ 203	$ 203	680	907	1,129
Net unrealized gains (losses) on derivative instruments | Amounts reclassified from AOCI
Accumulated other comprehensive income [Line Items]
Interest and fees on loans									(165)	(27)	61
Less: Income tax expense (benefit)									(41)	(6)	15
Net income									(124)	(21)	46
Net unrealized gains (losses) on investment securities | Amounts reclassified from AOCI
Accumulated other comprehensive income [Line Items]
Securities gains (losses), net									(276)	(53)	0
Less: Income tax expense (benefit)									(68)	(13)	0
Net income									$ (208)	$ (40)	$ 0