Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ 941			$ 617			$ 2,624	$ 1,553
Income tax expense	52			78			223	183
Other expense	42			33			137	128
Amounts reclassified from AOCI	(142)	$ (329)	$ (255)	(268)	$ (177)	$ (198)	(727)	(642)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	16			7			44	13
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	18			5			50	9
Income tax expense	(4)			(1)			(12)	(2)
Amounts reclassified from AOCI	14			4			38	7
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			4			8	8
Amounts reclassified from AOCI	$ 2			$ 3			$ 6	$ 6