Debt Narrative (details) (Details) - USD ($) $ in Millions	1 Months Ended
Debt Narrative (details) (Details) - USD ($) $ in Millions	Mar. 31, 2015	Sep. 30, 2013	Jun. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Forward starting interest rate swap agreement fixed rate	3.11%	4.73%
Long-term debt			$ 3,420.4	$ 2,678.2
Short-term Debt			0.0	749.8
$750.0 Million Fixed Rate Notes Due March 2030, Interest Equal To 4.4% [Abstract]
Debt Instrument [Line Items]
Long-term debt			741.2	0.0
$750.0 Million Fixed Rate Notes Due March 2025, stated rate of 3.00% [Member]
Debt Instrument [Line Items]
Short-term Debt			0.0	749.8
Debt Instrument, Face Amount			$ 750.0
Debt Instrument, Interest Rate, Stated Percentage			3.00%
Debt Instrument, Face Amount			$ 750.0
Debt Instrument, Interest Rate, Stated Percentage			3.00%
$500.0 Million Fixed Rate Notes Due June 2028, stated rate of 3.75% [Member] [Domain]
Debt Instrument [Line Items]
Long-term debt			$ 498.7	$ 498.5
Debt Instrument, Face Amount			$ 750.0
Debt Instrument, Interest Rate, Stated Percentage			4.40%
Debt Instrument, Face Amount			$ 750.0
Debt Instrument, Interest Rate, Stated Percentage			4.40%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

CME GROUP INC. 10-Q