STATEMENTS OF CHANGES IN CONSOLIDATED EQUITY - USD ($) $ in Millions	Total	[CommonStockMember]	[AdditionalPaidInCapitalMember]	[RetainedEarningsMember]	[TreasuryStockMember]	[AccumulatedOtherComprehensiveIncomeMember]	[NoncontrollingInterestMember]
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	136.1			130.8			5.3
Other comprehensive income	40.0					36.2	3.8
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	3.1		7.8	(0.2)	(4.5)
Total Stockholders' Equity at Jun. 30, 2018	2,041.9	12.7	1,604.1	1,330.4	(30.6)	(991.6)	116.9
Total Stockholders' Equity at Mar. 31, 2018	1,963.3	12.7	1,599.5	1,257.8	(31.7)	(992.2)	117.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	75.6			72.8			2.8
Other comprehensive income	(2.5)					0.6	(3.1)
Employee stock plans	5.5		4.6	(0.2)	1.1
Total Stockholders' Equity at Jun. 30, 2018	2,041.9	12.7	1,604.1	1,330.4	(30.6)	(991.6)	116.9
Total Stockholders' Equity at Dec. 31, 2018	1,991.6	12.7	1,615.4	1,422.0	(30.6)	(1,133.8)	105.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	94.8			90.1			4.7
Other comprehensive income	51.0					49.4	1.6
Employee stock plans	1.2		(10.8)	(0.3)	12.3
Total Stockholders' Equity at Jun. 30, 2019	2,138.6	12.7	1,604.6	1,511.8	(18.3)	(1,084.4)	112.2
Total Stockholders' Equity at Mar. 31, 2019	2,046.6	12.7	1,599.7	1,437.0	(19.7)	(1,095.5)	112.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	78.5			75.1			3.4
Other comprehensive income	7.5					11.1	(3.6)
Employee stock plans	6.0		4.9	(0.3)	1.4
Total Stockholders' Equity at Jun. 30, 2019	$ 2,138.6	$ 12.7	$ 1,604.6	$ 1,511.8	$ (18.3)	$ (1,084.4)	$ 112.2