Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock Issued [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock at Cost [Member]	Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2015	$ 101.6	$ 0.9	$ 1,002.4	$ 1,146.7	$ (204.7)	$ (1,844.1)	$ 0.4
Beginning balance, Treasury shares at Dec. 31, 2015						42,500,000
Stockholders' Equity [Roll Forward]
Net income	277.8			277.8
Dividends	(71.5)			(71.5)
Foreign currency translation adjustments, net	(11.6)				(11.6)
Pension and postretirement liability changes, net of tax expense (benefit)	9.3				9.3
Change in fair value of available-for-sale marketable equity securities	(2.1)				(2.1)
Stock-based compensation expense	31.7		31.7
Change in cash flow hedges, net of tax expense (benefit)	14.0				14.0
Treasury shares reissued for common stock	(2.7)		(7.3)			$ (10.0)
Treasury shares reissued for common stock, shares						(700,000)
Additional investment in subsidiary	0.0						0.0
Treasury stock purchases	(333.3)		0.0			$ (333.3)
Treasury stock purchases, shares						2,400,000
Tax benefits of stock-based compensation	19.4		19.4
Ending balance at Dec. 31, 2016	38.0	0.9	1,046.2	1,353.0	(195.1)	$ (2,167.4)	0.4
Ending balance, Treasury shares at Dec. 31, 2016						44,200,000
Stockholders' Equity [Roll Forward]
Net income	305.7			305.7
Dividends	(82.8)			(82.8)
Foreign currency translation adjustments, net	33.9				33.9
Pension and postretirement liability changes, net of tax expense (benefit)	2.5				2.5
Change in fair value of available-for-sale marketable equity securities	(0.5)				(0.5)
Stock-based compensation expense	24.9		24.9
Change in cash flow hedges, net of tax expense (benefit)	1.8				1.8
Treasury shares reissued for common stock	(3.1)		(9.6)			$ (12.7)
Treasury shares reissued for common stock, shares						(400,000)
Additional investment in subsidiary	(0.4)						(0.4)
Treasury stock purchases	(276.1)		0.0			$ (276.1)
Treasury stock purchases, shares						1,600,000
Ending balance at Dec. 31, 2017	$ 50.1	0.9	1,061.5	1,575.9	(157.4)	$ (2,430.8)	0.0
Ending balance, Treasury shares at Dec. 31, 2017	45,361,145					45,400,000
Stockholders' Equity [Roll Forward]
Cumulative Effect on Retained Earnings, Net of Tax	$ (6.2)			16.5	(22.7)
Net income	359.0			359.0
Dividends	(98.2)			(98.2)
Foreign currency translation adjustments, net	11.0				11.0
Pension and postretirement liability changes, net of tax expense (benefit)	(2.8)				(2.8)
Change in fair value of available-for-sale marketable equity securities	0.0			1.8	(1.8)
Stock-based compensation expense	26.3		26.3
Change in cash flow hedges, net of tax expense (benefit)	(15.1)				(15.1)
Treasury shares reissued for common stock	(3.4)		(9.0)			$ (12.4)
Treasury shares reissued for common stock, shares						(400,000)
Treasury stock purchases	(477.1)					$ (477.1)
Treasury stock purchases, shares						2,300,000
Ending balance at Dec. 31, 2018	$ (149.6)	$ 0.9	$ 1,078.8	$ 1,855.0	$ (188.8)	$ (2,895.5)	$ 0.0
Ending balance, Treasury shares at Dec. 31, 2018	47,312,248					47,300,000