Accumulated Other Comprehensive Income - Reclassification Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities gains (losses), net	$ 7	$ (32)	$ 11	$ (47)
Interest and fees on loans and leases	1,831	1,081	3,545	2,062
Compensation and benefits	(650)	(584)	(1,407)	(1,295)
Income (loss) before income taxes	775	724	1,493	1,335
Applicable income tax expense	(174)	(162)	(334)	(279)
Net income	601	562	1,159	1,056
Reclassification out of AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income	(64)	43	(114)	105
Reclassification out of AOCI | Available-for-sale debt securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities gains (losses), net	0	0	0	3
Income (loss) before income taxes	0	0	0	3
Applicable income tax expense	0	0	0	(1)
Net income	0	0	0	2
Reclassification out of AOCI | Net unrealized gains on cash flow hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest and fees on loans and leases	(81)	58	(146)	136
Income (loss) before income taxes	(81)	58	(146)	136
Applicable income tax expense	18	(13)	33	(30)
Net income	(63)	45	(113)	106
Reclassification out of AOCI | Net periodic benefit costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income (loss) before income taxes	(1)	(2)	(1)	(3)
Applicable income tax expense	0	0	0	0
Net income	(1)	(2)	(1)	(3)
Reclassification out of AOCI | Amortization of net actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Compensation and benefits	(1)	(1)	(1)	(2)
Reclassification out of AOCI | Settlements
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Compensation and benefits	$ 0	$ (1)	$ 0	$ (1)