Premises, Equipment, and Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Operating lease right-of-use assets	$ 345	$ 367
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Finance lease right-of-use assets	$ 3	$ 4
Total lease right-of-use assets	$ 348	$ 371
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Operating lease liabilities	$ 382	$ 407
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Finance lease liabilities	$ 4	$ 4
Total lease liabilities	$ 386	$ 411