CONDENSED CONSOLIDATED STATEMENT OF EQUITY (UNAUDITED) - 9 months ended Sep. 30, 2017 - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Dec. 31, 2016	$ 1,117.5	$ 18.4	$ 260.4	$ (46.1)	$ 1,071.6	$ (186.8)
Balance (in shares) at Dec. 31, 2016		73.7
Increase (Decrease) in Equity [Roll Forward]
Net income	150.7				150.7
Stock-based compensation	11.8		4.3	7.5
Shares issued under stock plans (shares)		1.4
Shares issued under stock plans	40.4	$ 0.3	33.9	6.2
Shares repurchased under share repurchase program	(26.9)			(26.9)
Shares repurchased for employee tax withholdings (shares)		0.0
Shares repurchased for employee tax withholdings	(3.8)		(0.4)	(3.4)
Dividends declared	(29.6)				(29.6)
Other adjustments to capital in excess of par value	(4.7)		(4.7)
Other comprehensive income, net of tax	56.2					56.2
Balance at Sep. 30, 2017	1,316.9	$ 18.7	$ 302.9	$ (62.7)	1,188.6	$ (130.6)
Balance (in shares) at Sep. 30, 2017		75.1
Increase (Decrease) in Equity [Roll Forward]
Effect of modified retrospective application of a new accounting standard	$ (4.1)				$ (4.1)