Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	APIC	Retained Earnings	AOCI
Beginning balance (in shares) at Dec. 31, 2022		46,767,164
Beginning balance at Dec. 31, 2022	$ 640.7	$ 0.5	$ (2,633.3)	$ 518.9	$ 2,755.1	$ (0.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	556.8				556.8
Gain on interest rate hedge and unrealized gain on marketable securities, net of tax	0.5					0.5
Cash dividends declared	(33.4)				(33.4)
Dividend equivalent units accrued	0.0			0.4	(0.4)
Purchase of treasury stock	(336.2)		(336.2)
Issuance of treasury stock	(0.2)		11.7	(11.9)
Amounts related to share-based compensation	(21.1)			(21.1)
Share-based compensation expense	21.8			21.8
Ending balance (in shares) at Dec. 31, 2023		46,767,164
Ending balance at Dec. 31, 2023	828.9	$ 0.5	(2,957.8)	508.1	3,278.1	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	502.5				502.5
Gain on interest rate hedge and unrealized gain on marketable securities, net of tax	0.0
Cash dividends declared	(36.8)				(36.8)
Dividend equivalent units accrued	0.0			0.4	(0.4)
Purchase of treasury stock	(446.6)		(446.6)
Issuance of treasury stock	(0.4)		13.1	(13.5)
Amounts related to share-based compensation	(30.4)			(30.4)
Share-based compensation expense	$ 22.9			22.9
Ending balance (in shares) at Dec. 31, 2024	46,767,164	46,767,164
Ending balance at Dec. 31, 2024	$ 840.1	$ 0.5	(3,391.3)	487.5	3,743.4	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	470.6				470.6
Gain on interest rate hedge and unrealized gain on marketable securities, net of tax	0.0
Cash dividends declared	(41.5)				(41.5)
Dividend equivalent units accrued	0.0			0.2	(0.2)
Purchase of treasury stock	(652.0)		(652.0)
Issuance of treasury stock	1.2		11.6	(10.4)
Amounts related to share-based compensation	(23.5)			(23.5)
Share-based compensation expense	$ 28.6			28.6
Ending balance (in shares) at Dec. 31, 2025	46,767,164	46,767,164
Ending balance at Dec. 31, 2025	$ 623.5	$ 0.5	$ (4,031.7)	$ 482.4	$ 4,172.3	$ 0.0