Premises, Equipment, and Leases - Schedule of Lease Liabilities Included in the Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
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	$ 321	$ 296
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Finance lease right-of-use assets	$ 2	$ 2
Total lease right-of-use assets	$ 323	$ 298
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Operating lease liabilities	$ 368	$ 330
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Finance lease liabilities	$ 2	$ 3
Total lease liabilities	$ 370	$ 333