Unaudited Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenues
Total revenues	$ 483.6	$ 437.5	$ 1,014.1	$ 937.4
Cost of revenues
Operating expenses	68.4	67.5	134.8	131.1
Depreciation and amortization	19.1	16.4	37.4	31.4
Total cost of revenues	87.5	83.9	172.2	162.5
Administrative expenses
Sales and marketing	116.0	106.9	226.9	222.4
Research and development	74.8	62.4	137.1	112.9
General and administrative	70.2	70.1	135.9	22.0
Depreciation and amortization	22.8	19.2	44.5	36.7
Total administrative expenses	283.8	258.5	544.4	393.9
Total operating expenses	371.3	342.4	716.6	556.4
Operating income	112.3	95.1	297.5	381.0
Interest expense	(0.8)	(0.8)	(1.6)	(1.6)
Other income (expense), net	5.7	4.8	11.6	9.8
Income before income taxes	117.2	99.1	307.5	389.2
Provision for income taxes	27.7	31.2	78.6	74.0
Net income	$ 89.5	$ 68.0	$ 228.9	$ 315.2
Earnings per share, basic	$ 1.59	$ 1.2	$ 4.08	$ 5.58
Earnings per share, diluted	$ 1.58	$ 1.2	$ 4.06	$ 5.57
Weighted average shares outstanding:
Basic	56,117	56,451	56,045	56,499
Diluted	56,500	56,771	56,324	56,548
Comprehensive earnings:
Net income	$ 89.5	$ 68.0	$ 228.9	$ 315.2
Unrealized net (losses) gains on available-for-sale securities	(0.1)	0.3	0.6	1.2
Tax effect	0.3	(0.1)	0.1	(0.4)
Other comprehensive income, net of tax	0.2	0.2	0.7	0.7
Comprehensive earnings:	89.7	68.2	229.6	315.9
Recurring and Other [Member]
Revenues
Total revenues	455.1	405.5	955.1	871.6
Interest on Funds Held for Clients [Member]
Revenues
Total revenues	$ 28.5	$ 32.0	$ 59.0	$ 65.8