Clearing Operations (Schedule of Derivative Contracts) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2026 USD ($) contract	Sep. 30, 2025 contract
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 1,507
Total number of derivative contracts cleared (in contracts)	56,315,700	55,697,783
Fixed-income swaps, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 961
Total number of derivative contracts cleared (in contracts)	14,674,211	14,269,081
Stock options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 374
Total number of derivative contracts cleared (in contracts)	19,598,045	17,875,224
Index options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 172
Total number of derivative contracts cleared (in contracts)	21,983,458	23,362,390
Commodity futures and forwards
Clearing Operations [Line Items]
Total number of derivative contracts cleared (in contracts)	59,986	191,088