Clearing Operations (Narrative) (Details)	6 Months Ended
	Jun. 30, 2026 USD ($) TWh contract	Jun. 30, 2025 USD ($) TWh contract	Dec. 31, 2025 USD ($)
Clearing Operations [Line Items]
Default fund contributions and margin deposits	$ 7,885,000,000
Payment for default funds and margin deposits	71,751,000,000	$ 45,490,000,000
Proceeds from default funds and margin deposits	72,291,000,000	$ 45,115,000,000
Liability due to market default	$ 0
Total volume in cleared power, in Terawatt hours (TWh) | TWh	117	272
Total number of derivative contracts cleared (in contracts) | contract	38,348,146	37,870,236
Liability Waterfall
Clearing Operations [Line Items]
Junior capital, cash deposits and pledged assets	$ 20,000,000
Senior capital, cash deposits and pledged assets	24,000,000
Committed capital	87,000,000
Nasdaq Clearing Members Cash Contributions
Clearing Operations [Line Items]
Default fund contributions and margin deposits	2,323,000,000		$ 5,842,000,000
Restricted cash and cash equivalents
Clearing Operations [Line Items]
Gain (loss) currency translation adjustment	(59,000,000)
Investments
Clearing Operations [Line Items]
Gain (loss) currency translation adjustment	$ (113,000,000)
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	$ 131,000,000
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	$ 1,200,000,000	$ 800,000,000
Total number of derivative contracts cleared (in contracts) | contract	1,271,156	1,606,945