Clearing Operations (Schedule of Derivative Contracts) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2026 USD ($) contract	Jun. 30, 2025 contract
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 1,424
Total number of derivative contracts cleared (in contracts)	38,348,146	37,870,236
Fixed-income swaps, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 872
Total number of derivative contracts cleared (in contracts)	9,502,827	8,657,081
Stock options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 387
Total number of derivative contracts cleared (in contracts)	13,473,382	11,785,557
Index options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 165
Total number of derivative contracts cleared (in contracts)	15,311,951	17,290,381
Commodity futures and forwards
Clearing Operations [Line Items]
Total number of derivative contracts cleared (in contracts)	59,986	137,217