Occupancy Expense and Information Systems and Communications Expense - Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Occupancy	Occupancy
Amortization of right-of-use assets	$ 47	$ 48
Interest on lease liabilities	3	3
Total finance lease expense	50	51
Sublease income	0	0
Net finance lease expense	50	51
Operating lease expense	179	168
Sublease income	(13)	(17)
Net operating lease expense	166	151
Net lease expense	216	202
Operating cash flows from finance leases	3	3
Operating cash flows from operating leases	193	179
Financing cash flows from finance leases	43	46
Operating leases	214	174
Finance leases	$ 64	$ 0