Clearing Operations (Schedule of Derivative Contracts) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2025 USD ($) contract	Sep. 30, 2024 contract
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 1,342
Total number of derivative contracts cleared (in contracts) \| contract	55,697,783	58,897,754
Commodity forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 18
Commodity and seafood options, futures and forwards
Clearing Operations [Line Items]
Total number of derivative contracts cleared (in contracts) \| contract	191,088	165,641
Fixed-income swaps, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 734
Total number of derivative contracts cleared (in contracts) \| contract	14,269,081	14,306,316
Stock options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 479
Total number of derivative contracts cleared (in contracts) \| contract	17,875,224	17,592,459
Index options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts \| $	$ 111
Total number of derivative contracts cleared (in contracts) \| contract	23,362,390	26,833,338