Accumulated Other Comprehensive Income - Reclassification Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities (losses) gains, net	$ (14)	$ 3
Interest and fees on loans and leases	983	1,030
Compensation and benefits	711	706
Income before income taxes	612	883
Applicable income tax expense	(118)	(189)
Net income	494	694
Reclassification out of AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income	61	45
Reclassification out of AOCI | Net unrealized gains on available-for-sale debt securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities (losses) gains, net	3	(15)
Income before income taxes	3	(15)
Applicable income tax expense	(1)	4
Net income	2	(11)
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	78	72
Income before income taxes	78	72
Applicable income tax expense	(18)	(15)
Net income	60	57
Reclassification out of AOCI | Net periodic benefit costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Compensation and benefits	(1)	(2)
Income before income taxes	(1)	(2)
Applicable income tax expense	0	1
Net income	$ (1)	$ (1)