Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Total revenues	$ 993.5	$ 816.8	$ 2,953.8	$ 2,628.4
Cost of revenues:
Total cost of revenues	551.1	447.3	1,669.2	1,542.8
Revenues less cost of revenues	442.4	369.5	1,284.6	1,085.6
Operating expenses:
Compensation and benefits	102.0	74.0	269.4	214.0
Depreciation and amortization	41.0	42.8	122.1	125.4
Technology support services	19.1	16.7	56.4	50.1
Professional fees and outside services	20.4	24.0	64.2	62.0
Travel and promotional expenses	6.1	2.3	14.5	5.8
Facilities costs	6.2	5.8	19.3	16.5
Acquisition-related costs	1.6	6.7	17.9	11.9
Goodwill impairment	0.8		460.9
Other expenses	8.4	6.5	20.8	14.6
Total operating expenses	205.6	178.8	1,045.5	500.3
Operating income	236.8	190.7	239.1	585.3
Non-operating (expenses) income:
Interest expense, net	(15.3)	(11.7)	(40.7)	(36.3)
Other income (expense), net	7.5	(5.2)	(1.3)	(3.1)
Income before income tax provision	229.0	173.8	197.1	545.9
Income tax provision	78.8	53.4	121.8	182.8
Net income	150.2	120.4	75.3	363.1
Net income allocated to participating securities	(0.6)	(0.4)	(0.6)	(1.1)
Net income allocated to common stockholders	$ 149.6	$ 120.0	$ 74.7	$ 362.0
Basic earnings per share (in dollars per share)	$ 1.41	$ 1.12	$ 0.70	$ 3.38
Diluted earnings per share (in dollars per share)	$ 1.41	$ 1.12	$ 0.70	$ 3.38
Basic weighted average shares outstanding (in shares)	106.2	106.8	106.4	107.0
Diluted weighted average shares outstanding (in shares)	106.4	107.0	106.6	107.2
Cash and spot markets
Revenues:
Total revenues	$ 434.2	$ 357.3	$ 1,354.6	$ 1,278.9
Data and access solutions
Revenues:
Total revenues	126.1	110.3	368.9	313.9
Derivatives markets
Revenues:
Total revenues	433.2	349.2	1,230.3	1,035.6
Liquidity payments
Cost of revenues:
Total cost of revenues	392.3	375.3	1,288.8	1,255.0
Routing and clearing
Cost of revenues:
Total cost of revenues	20.2	19.0	63.4	66.0
Section 31 fees
Cost of revenues:
Total cost of revenues	105.4	27.9	220.7	148.6
Royalty fees and other cost of revenues
Cost of revenues:
Total cost of revenues	$ 33.2	$ 25.1	$ 96.3	$ 73.2