STATEMENTS OF CHANGES IN CONSOLIDATED EQUITY - USD ($) $ in Millions	Total	[CommonStockMember]	[AdditionalPaidInCapitalMember]	[RetainedEarningsMember]	[TreasuryStockMember]	[AccumulatedOtherComprehensiveIncomeMember]	[NoncontrollingInterestMember]
Total Stockholders' Equity at Dec. 31, 2016	$ 1,444.8	$ 11.0	$ 1,188.8	$ 1,277.1	$ (28.0)	$ (1,093.7)	$ 89.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21.1			17.5			3.6
Other comprehensive income	24.3					22.3	2.0
Employee stock plans	(0.8)		(1.7)		0.9
Total Stockholders' Equity at Mar. 31, 2017	1,489.4	11.0	1,187.1	1,294.6	(27.1)	(1,071.4)	95.2
Total Stockholders' Equity at Dec. 31, 2017	1,844.5	12.7	1,596.3	1,184.3	(26.1)	(1,027.8)	105.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	60.5			58.0			2.5
Other comprehensive income	42.5					35.6	6.9
Cumulative effect of adoption of new accounting standard	15.5			15.5
Sales of subsidiary shares to noncontrolling interest	2.7						2.7
Employee stock plans	(2.4)		3.2		(5.6)
Total Stockholders' Equity at Mar. 31, 2018	$ 1,963.3	$ 12.7	$ 1,599.5	$ 1,257.8	$ (31.7)	$ (992.2)	$ 117.2