Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024		Dec. 31, 2023
Revenues
Total revenues	$ 2,051.7	$ 1,883.2		$ 1,693.7
Cost of revenues
Operating expenses	263.0	267.4		223.7
Depreciation and amortization	82.4	67.2		52.6
Total cost of revenues	345.4	334.6		276.3
Administrative expenses
Sales and marketing	482.8	434.4		417.6
Research and development	283.4	242.6		199.0
General and administrative	279.0	158.6		288.1
Depreciation and amortization	93.9	78.7		61.4
Total administrative expenses	1,139.1	914.3		966.1
Total operating expenses	1,484.5	1,248.9		1,242.4
Operating income	567.2	634.3		451.3
Interest expense	(3.4)	(3.4)		(1.9)
Other income, net	55.6	18.1		23.0
Income before income taxes	619.4	649.0		472.4
Provision for income taxes	166.0	147.0	[1]	131.6	[1]
Net income	$ 453.4	$ 502.0		$ 340.8
Earnings per share, basic	$ 8.13	$ 8.93		$ 5.91
Earnings per share, diluted	$ 8.08	$ 8.92		$ 5.88
Weighted average shares outstanding:
Basic	55,765	56,208		57,707
Diluted	56,116	56,296		57,974
Comprehensive earnings:
Net income	$ 453.4	$ 502.0		$ 340.8
Unrealized net gains on available-for-sale securities	1.0	1.0		3.5
Tax effect	(0.1)	(0.6)		(0.8)
Other comprehensive income, net of tax	0.9	0.4		2.7
Comprehensive earnings	454.3	502.4		343.5
Recurring and Other [Member]
Revenues
Total revenues	1,938.7	1,758.3		1,585.7
Interest on Funds Held for Clients [Member]
Revenues
Total revenues	$ 113.0	$ 124.9		$ 108.0

[1] Disclosures for 2024 and 2023 were adjusted for retrospective application of ASU 2023-09, as described in Note 2 “Summary of Significant Accounting Policies.”