Consolidated Statements Of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated other Comprehensive Income (Loss)	Non Controlling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest						$ 0.3
Beginning Balance at Dec. 31, 2018	$ 867.0	$ 0.6	$ 808.0	$ 121.1	$ (63.0)
Beginning Balance (in shares) at Dec. 31, 2018		60.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation	74.9	$ 0.0	74.9
Deferred compensation	(6.7)		(4.4)	(2.3)
Employee stock compensation (in shares)		0.4
Proceeds from stock issuances under employee plans	15.7	$ 0.0	15.7
Proceeds from stock issuances under employee plans (in shares)		0.2
Cash dividends declared ($2.32 per share, $2.20 per share and $2.12 per share in 2017, 2016, and 2015 respectively)	(149.1)			149.1
Repurchase and retirement of common shares	$ (8.4)	$ 0.0	(1.4)	(7.0)
Repurchase and retirement of common shares (in shares)	(0.1)	(0.1)
Cumulative effect of adoption of accounting standards	$ 0.0			0.6	(0.6)
Net income	324.0			324.0
Net income	323.9					(0.1)
Other comprehensive income	(9.1)				(9.1)
Ending Balance at Dec. 31, 2019	1,108.2	$ 0.6	892.8	287.3	(72.7)
Ending Balance (in shares) at Dec. 31, 2019		61.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest						0.2
Employee stock compensation	65.3	$ 0.0	65.3
Deferred compensation	1.3		0.5	0.8
Employee stock compensation (in shares)		0.6
Proceeds from stock issuances under employee plans	33.6	$ 0.0	33.6
Proceeds from stock issuances under employee plans (in shares)		0.5
Cash dividends declared ($2.32 per share, $2.20 per share and $2.12 per share in 2017, 2016, and 2015 respectively)	(152.5)			(152.5)
Repurchase and retirement of common shares	$ (50.3)	$ 0.0	(8.3)	(42.0)
Repurchase and retirement of common shares (in shares)	(0.6)	0.6
Net income	$ 124.8			124.8
Net income	124.9					0.1
Other comprehensive income	14.3				14.3
Ending Balance at Dec. 31, 2020	1,144.5
Ending Balance (in shares) at Dec. 31, 2020		61.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,144.8	$ 0.6	983.9	218.4	(58.4)	0.3
Employee stock compensation	62.7	$ 0.0	62.7
Deferred compensation	1.1		1.3	(0.2)
Employee stock compensation (in shares)		0.5
Proceeds from stock issuances under employee plans	156.1	$ 0.0	156.1
Proceeds from stock issuances under employee plans (in shares)		1.8
Cash dividends declared ($2.32 per share, $2.20 per share and $2.12 per share in 2017, 2016, and 2015 respectively)	(153.4)			(153.4)
Repurchase and retirement of common shares	$ (461.6)	$ 0.0	(60.2)	(401.4)
Repurchase and retirement of common shares (in shares)	(3.8)	(3.8)
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	$ 1.3					1.3
Net income	493.9
Net income	494.3			493.9		0.4
Other comprehensive income	(19.0)				(19.0)
Ending Balance at Dec. 31, 2021	1,224.3
Ending Balance (in shares) at Dec. 31, 2021		60.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 1,226.3	$ 0.6	$ 1,143.8	$ 157.3	$ (77.4)	$ 2.0