Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues:
Total revenues	$ 1,055.7	$ 908.8	$ 2,986.9	$ 2,804.8
Cost of revenues:
Total cost of revenues	523.7	428.3	1,439.0	1,385.8
Revenues less cost of revenues	532.0	480.5	1,547.9	1,419.0
Operating expenses:
Compensation and benefits	119.1	96.1	350.5	313.0
Depreciation and amortization	31.8	38.8	100.9	120.0
Technology support services	25.5	25.0	74.3	75.5
Professional fees and outside services	21.9	24.4	69.2	68.7
Travel and promotional expenses	12.6	8.9	29.4	28.6
Facilities costs	5.9	6.2	18.5	20.0
Acquisition-related costs	0.0	0.8	1.2	7.9
Impairment of intangible assets	0.0	0.0	81.0	0.0
Other expenses	7.8	9.1	23.0	21.4
Total operating expenses	224.6	209.3	748.0	655.1
Operating income	307.4	271.2	799.9	763.9
Non-operating (expenses) income:
Interest expense	(12.8)	(15.4)	(38.6)	(49.2)
Interest income	11.4	3.5	20.1	8.3
Earnings on investments	1.0	10.3	29.2	34.9
Other income (expense), net	2.0	0.5	(6.5)	2.2
Income before income tax provision	309.0	270.1	804.1	760.1
Income tax provision	90.5	61.9	235.7	210.7
Net income	218.5	208.2	568.4	549.4
Net income allocated to participating securities	(1.1)	(1.1)	(3.0)	(2.7)
Net income allocated to common stockholders	217.4	207.1	565.4	546.7
Net income allocated to common stockholders	$ 217.4	$ 207.1	$ 565.4	$ 546.7
Basic earnings per share (in USD per share)	$ 2.08	$ 1.96	$ 5.38	$ 5.17
Diluted earnings per share (in USD per share)	$ 2.07	$ 1.95	$ 5.36	$ 5.15
Basic weighted average shares outstanding (in shares)	104.7	105.7	105.2	105.8
Diluted weighted average shares outstanding (in shares)	105.1	106.1	105.6	106.2
Cash and spot markets
Revenues:
Total revenues	$ 434.1	$ 335.1	$ 1,201.4	$ 1,083.4
Data and access solutions
Revenues:
Total revenues	145.6	137.0	427.9	401.7
Derivatives markets
Revenues:
Total revenues	476.0	436.7	1,357.6	1,319.7
Liquidity payments
Cost of revenues:
Total cost of revenues	317.6	323.7	963.4	1,032.9
Routing and clearing
Cost of revenues:
Total cost of revenues	17.4	17.8	50.0	62.6
Section 31 fees
Cost of revenues:
Total cost of revenues	129.5	36.1	249.3	145.5
Royalty fees and other cost of revenues
Cost of revenues:
Total cost of revenues	$ 59.2	$ 50.7	$ 176.3	$ 144.8