Consolidated Statement of Changes in Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Shares Held in Trust [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]
Common Stock, Shares, Issued at Dec. 31, 2017	45,373,817
Balances at Dec. 31, 2017	$ 3,378.2	$ 0.5	$ 1,037.3	$ 2,649.0	$ (5.9)	$ (340.8)	$ 38.1
Increase (decrease) in shareholders' equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	42.6			40.3			2.3
Shares issued under stock compensation programs (in shares)		172,157
Shares issued under stock compensation programs	0.3		0.3
Shares repurchased for payment of taxes on stock awards (in shares)		(55,536)
Shares repurchased for payment of taxes on stock awards	(8.7)		(8.7)
Amortization of stock compensation	8.8		8.8
(Increase) Decrease In Common Stock Held In Trust	(0.1)				(0.1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax						0.0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	0.0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						51.8
Foreign currency translation adjustments	51.8
Distributions to noncontrolling interest	0.5						0.5
Noncontrolling Interest, Change in Redemption Value	$ 2.3		2.3
Common Stock, Shares, Issued at Mar. 31, 2018	45,490,438
Balances at Mar. 31, 2018	$ 3,475.7	$ 0.5	1,040.0	2,689.3	(6.0)	(289.0)	40.9
Common Stock, Shares, Issued at Dec. 31, 2018	45,599,418
Balances at Dec. 31, 2018	$ 3,734.5	$ 0.5	1,057.3	3,095.7	(5.8)	(456.2)	43.0
Increase (decrease) in shareholders' equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	21.2			21.3			(0.1)
Shares issued under stock compensation programs (in shares)		198,575
Shares issued under stock compensation programs	2.0		2.0
Shares repurchased for payment of taxes on stock awards (in shares)		(58,750)
Shares repurchased for payment of taxes on stock awards	(9.7)		(9.7)
Amortization of stock compensation	7.0		7.0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	(1.0)					(1.0)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						31.3
Foreign currency translation adjustments	31.3
Distributions to noncontrolling interest	$ 9.8						9.8
Common Stock, Shares, Issued at Mar. 31, 2019	45,739,243
Balances at Mar. 31, 2019	$ 3,795.1	$ 0.5	$ 1,056.6	$ 3,117.0	$ (5.8)	$ (425.9)	$ 52.7