INVESTMENTS - Schedule of investments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Schedule of Cost and Equity Method Investments
Total equity method investments	$ 216.0		$ 209.5
Total other equity investments	37.6		36.3
Total investments	253.6		245.8
Investment in 7Ridge Investments 3 LP
Schedule of Cost and Equity Method Investments
Total equity method investments	216.0		209.5
Investment in Eris Exchange Holdings, LLC
Schedule of Cost and Equity Method Investments
Total other equity investments	20.0		20.0
Investment in CSD Br
Schedule of Cost and Equity Method Investments
Total other equity investments	5.9	$ 5.9
Investment in Coin Metrics Inc.
Schedule of Cost and Equity Method Investments
Total other equity investments	5.0	$ 5.0
Investment in Cboe Vest Financial Group, Inc.
Schedule of Cost and Equity Method Investments
Total other equity investments	2.9		2.9
Investment in Effective Investing Limited
Schedule of Cost and Equity Method Investments
Total other equity investments	1.8
Investment in OCC
Schedule of Cost and Equity Method Investments
Total other equity investments	$ 0.3		0.3
Investment percentage	20.00%
Investment in American Financial Exchange, LLC
Schedule of Cost and Equity Method Investments
Total other equity investments			10.6
Investment in Eris Digital Holdings, LLC
Schedule of Cost and Equity Method Investments
Total other equity investments			1.1
Other equity investments
Schedule of Cost and Equity Method Investments
Total other equity investments	$ 1.7		$ 1.4