Clearing Operations (Narrative) (Details)	9 Months Ended
Clearing Operations (Narrative) (Details)	Sep. 30, 2025 USD ($) contract	Sep. 30, 2024 USD ($) contract	Dec. 31, 2024 USD ($)
Clearing Operations [Line Items]
Default fund contributions	$ 1,453,000,000
Default fund contributions and margin deposits	11,960,000,000
Payment for default funds and margin deposits	70,866,000,000	$ 27,301,000,000
Proceeds from default funds and margin deposits	70,447,000,000	$ 27,538,000,000
Liability due to market default	$ 0
Total number of derivative contracts cleared (in contracts) \| contract	55,697,783	58,897,754
Liability Waterfall
Clearing Operations [Line Items]
Junior capital, cash deposits and pledged assets	$ 46,000,000
Senior capital, cash deposits and pledged assets	24,000,000
Committed capital	89,000,000
Utilize as Capital Resources
Clearing Operations [Line Items]
Default fund contributions	1,368,000,000
Utilize as Member Posted Surplus Balance
Clearing Operations [Line Items]
Default fund contributions	85,000,000
Nasdaq Clearing Members Cash Contributions
Clearing Operations [Line Items]
Default fund contributions	1,275,000,000
Default fund contributions and margin deposits	5,750,000,000		$ 5,664,000,000
Restricted Cash and Equivalents
Clearing Operations [Line Items]
Currency translation adjustment	627,000,000
Investments
Clearing Operations [Line Items]
Currency translation adjustment	$ 306,000,000
Minimum
Clearing Operations [Line Items]
Reverse purchase agreements, maturity range	1 day
Maximum
Clearing Operations [Line Items]
Reverse purchase agreements, maturity range	8 days
Nasdaq Clearing
Clearing Operations [Line Items]
Committed capital	$ 159,000,000
Power of assessment of the clearing member's contribution to the financial markets and commodities markets default funds (as a percent)	230.00%
Contract value of resale and repurchase agreements	$ 1,400,000,000	$ 2,100,000,000
Total number of derivative contracts cleared (in contracts) \| contract	2,812,945	3,706,152