Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions		Total	Common Stock Outstanding	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Shares in Treasury
Balance at beginning (in shares) at Dec. 31, 2020			52.9
Balance at the beginning of the period at Dec. 31, 2020		$ 2,537.7	$ 78.7	$ 441.7	$ (97.0)	$ 3,928.7	$ (1,814.4)
Balance at beginning (in shares) at Dec. 31, 2020							25.5
Increase (Decrease) in Shareholders' Equity
Net income		421.7				421.7
Other comprehensive income (loss), net of tax		(8.2)			(8.2)
Dividends		(112.7)				(112.7)
Repurchase of common stock (in shares)			1.9				1.9
Repurchases of common stock		(315.6)					$ (315.6)
Issuance and deferrals, net for stock-based compensation (in shares)	[1]		(1.0)				(1.0)
Issuance and deferrals, net for stock based compensation	[1]	106.6		39.8			$ 66.8
Balance at ending (in shares) at Dec. 31, 2021			52.0
Balance at the end of the period at Dec. 31, 2021		2,629.5	$ 78.7	481.5	(105.2)	4,237.7	$ (2,063.2)
Balance at ending (in shares) at Dec. 31, 2021							26.4
Increase (Decrease) in Shareholders' Equity
Net income		924.0				924.0
Other comprehensive income (loss), net of tax		(52.6)			(52.6)
Dividends		(134.6)				(134.6)
Repurchase of common stock (in shares)			1.6				1.6
Repurchases of common stock		(400.0)					$ (400.0)
Issuance and deferrals, net for stock-based compensation (in shares)	[1]		(0.5)				0.5
Issuance and deferrals, net for stock based compensation	[1]	$ 58.1		31.1			$ 27.0
Balance at ending (in shares) at Dec. 31, 2022		50.9	50.9
Balance at the end of the period at Dec. 31, 2022		$ 3,024.4	$ 78.7	512.6	(157.8)	5,027.1	$ (2,436.2)
Balance at ending (in shares) at Dec. 31, 2022		27.5					27.5
Increase (Decrease) in Shareholders' Equity
Net income		$ 767.4				767.4
Other comprehensive income (loss), net of tax		46.7			46.7
Dividends		(160.5)				(160.5)
Repurchase of common stock (in shares)			3.5				3.5
Repurchases of common stock		(900.0)					$ (900.0)
Issuance and deferrals, net for stock-based compensation (in shares)	[1]		(0.3)				0.1
Issuance and deferrals, net for stock based compensation	[1]	$ 51.0		41.2			$ 9.8
Balance at ending (in shares) at Dec. 31, 2023		47.7	47.7
Balance at the end of the period at Dec. 31, 2023		$ 2,829.0	$ 78.7	$ 553.8	$ (111.1)	$ 5,634.0	$ (3,326.4)
Balance at ending (in shares) at Dec. 31, 2023		30.9					30.9

[1] Issuances and deferrals, net for stock-based compensation reflects share activity related to option exercises, net of tax, restricted and performance shares vested, and net issuances and deferrals associated with deferred compensation equity.