CONSOLIDATED STATEMENT OF EQUITY - USD ($) $ in Millions	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Balance at Dec. 31, 2015	$ 1,023.9	$ 18.1	$ 207.8	$ (4.0)	$ 964.6	$ (162.6)
Balance (in shares) at Dec. 31, 2015		72,400,000		100,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	143.6				143.6
Stock-based compensation	17.3	$ 0.0	17.1	$ 0.2
Shares issued under stock plans (in shares)		1,400,000		0
Shares issued under stock plans	31.2	$ 0.3	21.0	$ 9.9
Shares purchased under share repurchase program (in shares)				500,000
Shares purchased under share repurchase program	(52.2)			$ (52.2)
Shares repurchased for employee tax withholdings (in shares)		(100,000)
Shares repurchased for employee tax withholdings	(3.7)		(3.7)	$ 0.0
Excess tax benefit from employee stock plans	18.2		18.2
Dividends declared	(36.6)				(36.6)
Other comprehensive income (loss), net of tax	(24.2)					(24.2)
Balance (in shares) at Dec. 31, 2016		73,700,000		600,000
Balance at Dec. 31, 2016	1,117.5	$ 18.4	260.4	$ (46.1)	1,071.6	(186.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	150.7				150.7
Stock-based compensation	14.0	$ 0.0	6.5	$ 7.5
Shares issued under stock plans (in shares)		1,500,000		(100,000)
Shares issued under stock plans	45.7	$ 0.4	38.0	$ 7.3
Shares purchased under share repurchase program (in shares)				800,000
Shares purchased under share repurchase program	(74.4)			$ (74.4)
Shares repurchased for employee tax withholdings (in shares)		0
Shares repurchased for employee tax withholdings	(3.8)		(0.4)	$ (3.4)
Dividends declared	(40.0)				(40.0)
Other adjustments to capital in excess of par value	(4.8)		(4.8)
Other comprehensive income (loss), net of tax	69.5					69.5
Balance (in shares) at Dec. 31, 2017		75,200,000		1,300,000
Balance at Dec. 31, 2017	1,279.9	$ 18.8	309.3	$ (109.1)	1,178.2	(117.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of modified retrospective application of new accounting standard	(4.1)				(4.1)
Net income	206.9				206.9
Stock-based compensation	16.5	$ 0.0	7.3	$ 9.2
Shares issued under stock plans (in shares)		100,000		(900,000)
Shares issued under stock plans	$ 36.8	$ 0.0	(34.8)	$ 71.6
Shares purchased under share repurchase program (in shares)	800,000			800,000
Shares purchased under share repurchase program	$ (70.8)			$ (70.8)
Shares repurchased for employee tax withholdings (in shares)		0
Shares repurchased for employee tax withholdings	(4.4)		0.2	$ (4.6)
Dividends declared	(43.1)				(43.1)
Other comprehensive income (loss), net of tax	(36.9)					(36.9)
Balance (in shares) at Dec. 31, 2018		75,300,000		1,200,000
Balance at Dec. 31, 2018	1,396.3	$ 18.8	$ 282.0	$ (103.7)	1,353.4	$ (154.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of modified retrospective application of new accounting standard	$ 11.4				$ 11.4