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	(84.9)			(93.6)			8.7
Other comprehensive income	84.6					77.4	7.2
Dividends to noncontrolling interests	(8.0)						(8.0)
Sales of subsidiary shares to noncontrolling interest	2.2						2.2
Employee stock plans	8.8		7.6	(0.9)	2.1
Total Stockholders' Equity at Sep. 30, 2017	1,447.5	11.0	1,196.4	1,182.6	(25.9)	(1,016.3)	99.7
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	191.7			181.3			10.4
Other comprehensive income	31.3					36.5	(5.2)
Cumulative effect of adoption of new accounting standard	15.5			15.5
Dividends to noncontrolling interests	(10.0)						(10.0)
Sales of subsidiary shares to noncontrolling interest	2.7						2.7
Employee stock plans	7.5		12.2	(0.2)	(4.5)
Total Stockholders' Equity at Sep. 30, 2018	$ 2,083.2	$ 12.7	$ 1,608.5	$ 1,380.9	$ (30.6)	$ (991.3)	$ 103.0