Occupancy Expense and Information Systems and Communications Expense - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Depreciation and amortization	$ 859	$ 858	$ 842
Finance lease right-of-use asset	$ 135	$ 55
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Premises and equipment (net of accumulated depreciation of $5,391 and $4,825)	Premises and equipment (net of accumulated depreciation of $5,391 and $4,825)
Finance lease liability	$ 164	$ 103
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Long-term debt	Long-term debt
Finance lease, accumulated amortization	$ 101
Interest on lease liabilities	6	$ 9
Right-of-use assets	$ 542	$ 720
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Lease liabilities	$ 689
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Accrued expenses and other liabilities
Operating leases not yet commenced	$ 455
Operating leases not yet commenced, lease terms	15 years