Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenues:
Total revenues	$ 1,173.5	$ 974.0	$ 2,368.5	$ 1,931.2
Cost of revenues:
Total cost of revenues	586.2	460.2	1,216.0	915.3
Revenues less cost of revenues	587.3	513.8	1,152.5	1,015.9
Operating expenses:
Compensation and benefits	127.9	116.1	244.1	231.4
Depreciation and amortization	29.9	31.8	60.2	69.1
Technology support services	26.7	24.6	52.3	48.8
Professional fees and outside services	24.8	25.8	45.6	47.3
Travel and promotional expenses	8.2	9.3	14.6	16.8
Facilities costs	7.0	6.1	13.2	12.6
Acquisition-related costs	0.0	0.6	0.2	1.2
Impairment of intangible assets	17.1	81.0	17.1	81.0
Other expenses	6.6	8.4	12.2	15.2
Total operating expenses	248.2	303.7	459.5	523.4
Operating income	339.1	210.1	693.0	492.5
Non-operating (expense) income:
Interest expense	(12.9)	(12.8)	(25.7)	(25.8)
Interest income	11.3	4.6	19.7	8.7
(Loss) earnings on investments, net	(1.1)	14.2	(4.4)	28.2
Other (expense) income, net	(1.8)	(13.1)	2.2	(8.5)
Income (loss) before income tax provision	334.6	203.0	684.8	495.1
Income tax provision	99.5	62.6	199.1	145.2
Net income	235.1	140.4	485.7	349.9
Net income allocated to participating securities	(1.2)	(0.7)	(2.4)	(1.9)
Net income allocated to participating securities	(1.2)	(0.7)	(2.4)	(1.9)
Net income allocated to common stockholders	233.9	139.7	483.3	348.0
Net income allocated to common stockholders	$ 233.9	$ 139.7	$ 483.3	$ 348.0
Basic earnings per share (in USD per share)	$ 2.23	$ 1.33	$ 4.62	$ 3.30
Diluted earnings per share (in USD per share)	$ 2.23	$ 1.33	$ 4.60	$ 3.29
Basic weighted average shares outstanding (in shares)	104.7	105.1	104.7	105.4
Diluted weighted average shares outstanding (in shares)	105.0	105.4	105.0	105.8
Cash and spot markets
Revenues:
Total revenues	$ 487.6	$ 386.4	$ 988.5	$ 767.3
Data Vantage
Revenues:
Total revenues	158.3	142.1	310.8	282.3
Derivatives markets
Revenues:
Total revenues	527.6	445.5	1,069.2	881.6
Liquidity payments
Cost of revenues:
Total cost of revenues	418.0	307.0	812.8	645.8
Routing and clearing
Cost of revenues:
Total cost of revenues	20.7	16.6	40.3	32.6
Section 31 fees
Cost of revenues:
Total cost of revenues	85.3	77.7	238.4	119.8
Royalty fees and other cost of revenues
Cost of revenues:
Total cost of revenues	$ 62.2	$ 58.9	$ 124.5	$ 117.1