Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Stated Capital	Other Paid-In Capital	Earnings Invested in the Business	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest	Holme Service Limited [Member]	Holme Service Limited [Member] Noncontrolling Interest
Beginning Balance at Dec. 31, 2014	$ 1,594.3	$ 53.1	$ 899.4	$ 1,128.5	$ 9.4	$ (509.2)	$ 13.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	191.4			188.6			2.8
Foreign currency translation adjustments	(64.8)				(62.7)		(2.1)
Pension and postretirement liability adjustment (net of income tax of $6.2 million, $13.1 million and $1.1 million for 2015, 2016 and 2017, respectively)	(2.4)				(2.4)
Change in fair value of derivative financial instruments, net of reclassifications	1.1				1.1
Payments to Acquire Interest in Joint Venture	6.9							$ 6.6	$ 6.6
Dividends declared to noncontrolling interest	(0.2)						(0.2)
Dividends - $1.03, $1.04 and $1.07 per share for 2015, 2016 and 2017, respectively	(87.0)			(87.0)
Tax shortfall from stock compensation	(1.5)		(1.5)
Stock-based compensation expense	18.4		18.4
Purchase of treasury shares	(309.7)					(309.7)
Stock option exercise activity	4.2		(7.5)			11.7
Restricted share activity	0.2		(6.7)			6.9
Ending Balance at Dec. 31, 2015	1,349.6	53.1	905.1	1,230.1	(54.6)	(804.3)	20.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Payments Related to Tax Withholding for Share-based Compensation	(4.0)					(4.0)
Net income (loss)	141.1			140.8			0.3
Foreign currency translation adjustments	(22.8)				(24.5)		1.7
Pension and postretirement liability adjustment (net of income tax of $6.2 million, $13.1 million and $1.1 million for 2015, 2016 and 2017, respectively)	1.1				1.1
Change in fair value of derivative financial instruments, net of reclassifications	0.1				0.1
Payments to Acquire Interest in Joint Venture	9.7							$ 9.3	$ 9.3
Dividends declared to noncontrolling interest	(0.3)						(0.3)
Dividends - $1.03, $1.04 and $1.07 per share for 2015, 2016 and 2017, respectively	(81.6)			(81.6)
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(1.1)		(1.1)
Stock-based compensation expense	14.1		14.1
Purchase of treasury shares	(101.0)					(101.0)
Stock option exercise activity	4.3		(2.5)			6.8
Restricted share activity	0.0		(8.7)			8.7
Ending Balance at Dec. 31, 2016	1,310.9	53.1	906.9	1,289.3	(77.9)	(891.7)	31.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Payments Related to Tax Withholding for Share-based Compensation	(1.9)					(1.9)
Net income (loss)	202.3			203.4			(1.1)
Foreign currency translation adjustments	47.1				44.7		2.4
Pension and postretirement liability adjustment (net of income tax of $6.2 million, $13.1 million and $1.1 million for 2015, 2016 and 2017, respectively)	(1.8)				(1.8)
Change in fair value of derivative financial instruments, net of reclassifications	(3.3)				(3.3)
Dividends declared to noncontrolling interest	(0.3)						(0.3)
Dividends - $1.03, $1.04 and $1.07 per share for 2015, 2016 and 2017, respectively	(83.3)			(83.3)
Stock-based compensation expense	24.7		24.7
Purchase of treasury shares	(43.4)					(43.4)
Stock option exercise activity	32.9		(10.7)			43.6
Restricted share activity	0.0		(18.6)			18.6
Ending Balance at Dec. 31, 2017	1,474.9	$ 53.1	$ 903.8	$ 1,408.4	$ (38.3)	(884.3)	$ 32.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Payments Related to Tax Withholding for Share-based Compensation	$ (11.4)					$ (11.4)