Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ 996			$ 941			$ 2,923	$ 2,624
Income tax expense	58			52			171	223
Other expense	56			42			142	137
Amounts reclassified from AOCI	(223)	$ (204)	$ (197)	(142)	$ (329)	$ (255)	(624)	(727)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	15			16			45	44
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	17			18			51	50
Income tax expense	(4)			(4)			(12)	(12)
Amounts reclassified from AOCI	13			14			39	38
Reclassification out of Accumulated Other Comprehensive Income | Pension and Post-retirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	(1)			(1)			(2)	(2)
Other expense	3			3			8	8
Amounts reclassified from AOCI	$ 2			$ 2			$ 6	$ 6