Unaudited Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Beginning balance, value at Dec. 31, 2023	$ 1,303.0	$ 0.6	$ 724.4	$ 1,470.0	$ (1.0)	$ (891.0)
Beginning balance, shares at Dec. 31, 2023		62.7
Treasury Stock, beginning balance, shares at Dec. 31, 2023						6.1
Stock-based compensation	(89.6)		(89.6)
Dividends declared	(20.0)			(20.0)
Repurchases of common stock	(3.1)					$ (3.1)
Repurchases of common stock, shares						0.1
Net income	247.2			247.2
Other comprehensive earnings (loss), net of tax	0.5				0.5
Treasury Stock, ending balance, shares at Mar. 31, 2024						6.2
Ending balance, value at Mar. 31, 2024	1,438.1	$ 0.6	634.8	1,697.2	(0.5)	$ (894.1)
Ending balance, shares at Mar. 31, 2024		62.7
Beginning balance, value at Dec. 31, 2023	1,303.0	$ 0.6	724.4	1,470.0	(1.0)	$ (891.0)
Beginning balance, shares at Dec. 31, 2023		62.7
Treasury Stock, beginning balance, shares at Dec. 31, 2023						6.1
Net income	315.2
Treasury Stock, ending balance, shares at Jun. 30, 2024						6.7
Ending balance, value at Jun. 30, 2024	1,426.5	$ 0.6	667.2	1,743.6	(0.3)	$ (984.6)
Ending balance, shares at Jun. 30, 2024		62.9
Beginning balance, value at Mar. 31, 2024	1,438.1	$ 0.6	634.8	1,697.2	(0.5)	$ (894.1)
Beginning balance, shares at Mar. 31, 2024		62.7
Treasury Stock, beginning balance, shares at Mar. 31, 2024						6.2
Vesting of restricted stock, shares		0.2
Stock-based compensation	32.4		32.4
Dividends declared	(21.6)			(21.6)
Repurchases of common stock	(90.5)					$ (90.5)
Repurchases of common stock, shares						0.6
Net income	68.0			68.0
Other comprehensive earnings (loss), net of tax	0.2				0.2
Treasury Stock, ending balance, shares at Jun. 30, 2024						6.7
Ending balance, value at Jun. 30, 2024	1,426.5	$ 0.6	667.2	1,743.6	(0.3)	$ (984.6)
Ending balance, shares at Jun. 30, 2024		62.9
Beginning balance, value at Dec. 31, 2024	$ 1,575.9	$ 0.6	724.8	1,887.5	(0.6)	$ (1,036.4)
Beginning balance, shares at Dec. 31, 2024		63.0
Treasury Stock, beginning balance, shares at Dec. 31, 2024	7.1					7.1
Vesting of restricted stock, shares		0.1
Stock-based compensation	$ 28.0		28.0
Dividends declared	(21.4)			(21.4)
Repurchases of common stock	(5.2)					$ (5.2)
Net income	139.4			139.4
Other comprehensive earnings (loss), net of tax	0.5				0.5
Treasury Stock, ending balance, shares at Mar. 31, 2025						7.1
Ending balance, value at Mar. 31, 2025	1,717.2	$ 0.6	752.8	2,005.5	(0.1)	$ (1,041.6)
Ending balance, shares at Mar. 31, 2025		63.1
Beginning balance, value at Dec. 31, 2024	$ 1,575.9	$ 0.6	724.8	1,887.5	(0.6)	$ (1,036.4)
Beginning balance, shares at Dec. 31, 2024		63.0
Treasury Stock, beginning balance, shares at Dec. 31, 2024	7.1					7.1
Net income	$ 228.9
Treasury Stock, ending balance, shares at Jun. 30, 2025	7.2					7.2
Ending balance, value at Jun. 30, 2025	$ 1,801.9	$ 0.6	801.9	2,073.3	0.2	$ (1,074.1)
Ending balance, shares at Jun. 30, 2025		63.5
Beginning balance, value at Mar. 31, 2025	1,717.2	$ 0.6	752.8	2,005.5	(0.1)	$ (1,041.6)
Beginning balance, shares at Mar. 31, 2025		63.1
Treasury Stock, beginning balance, shares at Mar. 31, 2025						7.1
Vesting of restricted stock, shares		0.4
Stock-based compensation	49.1		49.1
Dividends declared	(21.6)			(21.6)
Repurchases of common stock	(32.5)					$ (32.5)
Repurchases of common stock, shares						0.1
Net income	89.5			89.5
Other comprehensive earnings (loss), net of tax	$ 0.2				0.2
Treasury Stock, ending balance, shares at Jun. 30, 2025	7.2					7.2
Ending balance, value at Jun. 30, 2025	$ 1,801.9	$ 0.6	$ 801.9	$ 2,073.3	$ 0.2	$ (1,074.1)
Ending balance, shares at Jun. 30, 2025		63.5