Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ (955)			$ (996)			$ (2,770)	$ (2,923)
Income tax expense	78			58			205	171
Other expense	52			56			133	142
Total reclassification from AOCI	(266)	$ (245)	$ (222)	(223)	$ (204)	$ (197)	(732)	(624)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassification from AOCI	11			15			33	45
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	12			17			36	51
Income tax expense	(3)			(4)			(9)	(12)
Total reclassification from AOCI	9			13			27	39
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
Total reclassification from AOCI	$ 2			$ 2			$ 6	$ 6