SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended		183 Months Ended
	May 01, 2026	Apr. 29, 2026	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Apr. 22, 2026
Subsequent Events
Number of shares of common stock repurchased (in shares)			161,227	144,753	21,224,927
Average price paid per share (in dollars per share)			$ 280.20	$ 207.04	$ 81.54
Total purchase price			$ 45.1	$ 30.0	$ 1,700.0
Availability remaining under existing share repurchase authorizations			$ 569.4	$ 649.8	$ 569.4
Subsequent Event
Subsequent Events
Expected number of positions eliminated, percentage	20.00%
Number of shares of common stock repurchased (in shares)		5,000
Average price paid per share (in dollars per share)		$ 279.76
Total purchase price		$ 1.4
Subsequent Event | 2011 Share Repurchase Program
Subsequent Events
Availability remaining under existing share repurchase authorizations		$ 568.0
Subsequent Event | Disposal Group, Held-for-Sale, Not Discontinued Operations | Cboe Australia and Cboe Canada
Subsequent Events
Sale of business, expected consideration						$ 300.0
Subsequent Event | Minimum
Subsequent Events
Incurred pre-tax restructuring charges	$ 36.0
Restructuring, expected cost savings	40.0
Restructuring, expected cost savings, remainder of fiscal year	20.0
Subsequent Event | Maximum
Subsequent Events
Incurred pre-tax restructuring charges	46.0
Restructuring, expected cost savings	50.0
Restructuring, expected cost savings, remainder of fiscal year	$ 25.0