Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Noncontrolling Interest - Change in Stockholders' Equity (Deficit) (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Beginning Balance	$ 112.8	$ 75.9	$ 5.2	$ (7.4)	$ 75.9	$ (7.4)
Beginning Balance, shares		37,656,505			37,656,505
Beginning Balance Treasury Stock, shares		212,500			212,500
Net income	16.5	$ 29.6	17.4	10.6	$ 46.1	28.0
Foreign currency translation	0.8	3.0	(2.3)	(1.4)
Foreign currency loss on intra-entity transactions			(1.0)	(1.3)
Changes in defined benefit pension and other post-retirement benefit plans, net of tax	0.8	0.9	0.9	1.0
Stock-based compensation expense	0.8	0.8	1.0	0.7
Purchase of subsidiary shares from noncontrolling interest			(0.2)
Cash flow hedge - interest rate swap, net of tax	(0.6)	(0.4)	0.2	0.7
Ending Balance	$ 131.1	112.8	21.2	5.2	$ 131.1	21.2
Ending Balance, shares	37,996,261				37,996,261
Ending Balance Treasury Stock, shares	212,500				212,500
ASC 842 [Member]
Adoption of accounting principal		3.0
ASC 606 [Member]
Adoption of accounting principal				2.3
Common Stock [Member]
Beginning Balance	$ 0.4	$ 0.4	$ 0.4	$ 0.4	$ 0.4	$ 0.4
Beginning Balance, shares	37,666,000	37,656,000	37,421,000	37,421,000	37,656,000	37,421,000
Stock-based compensation expense, shares	330,000	10,000	87,000
Ending Balance	$ 0.4	$ 0.4	$ 0.4	$ 0.4	$ 0.4	$ 0.4
Ending Balance, shares	37,996,000	37,666,000	37,508,000	37,421,000	37,996,000	37,508,000
Treasury Stock [Member]
Beginning Balance	$ (6.6)	$ (6.6)	$ (6.6)	$ (6.6)	$ (6.6)	$ (6.6)
Beginning Balance Treasury Stock, shares	213,000	213,000	213,000	213,000	213,000	213,000
Ending Balance	$ (6.6)	$ (6.6)	$ (6.6)	$ (6.6)	$ (6.6)	$ (6.6)
Ending Balance Treasury Stock, shares	213,000	213,000	213,000	213,000	213,000	213,000
Capital in Excess of Par Value [Member]
Beginning Balance	$ 381.8	$ 381.0	$ 378.3	$ 377.6	$ 381.0	$ 377.6
Stock-based compensation expense	0.8	0.8	1.0	0.7
Purchase of subsidiary shares from noncontrolling interest	(2.9)		0.1
Ending Balance	379.7	381.8	379.4	378.3	379.7	379.4
Retained Earnings (Accumulated Deficit) [Member]
Beginning Balance	46.7	14.2	(81.4)	(95.1)	14.2	(95.1)
Net income	16.4	29.5	17.5	10.4
Ending Balance	63.1	46.7	(63.9)	(81.4)	63.1	(63.9)
Retained Earnings (Accumulated Deficit) [Member] | ASC 842 [Member]
Adoption of accounting principal		3.0
Retained Earnings (Accumulated Deficit) [Member] | ASU 2016-01 [Member]
Adoption of accounting principal				1.0
Retained Earnings (Accumulated Deficit) [Member] | ASC 606 [Member]
Adoption of accounting principal				2.3
Foreign Currency Translation [Member]
Beginning Balance	(49.9)	(52.8)	(44.3)	(41.6)	(52.8)	(41.6)
Foreign currency translation	0.8	2.9	(2.4)	(1.4)
Foreign currency loss on intra-entity transactions			(1.0)	(1.3)
Ending Balance	(49.1)	(49.9)	(47.7)	(44.3)	(49.1)	(47.7)
Benefit Plan Liabilities [Member]
Beginning Balance	(263.1)	(264.0)	(245.3)	(246.3)	(264.0)	(246.3)
Changes in defined benefit pension and other post-retirement benefit plans, net of tax	0.8	0.9	0.9	1.0
Ending Balance	(262.3)	(263.1)	(244.4)	(245.3)	(262.3)	(244.4)
Cash Flow Hedge - Interest Rate Swap [Member]
Beginning Balance	0.6	1.0	1.3	0.6	1.0	0.6
Cash flow hedge - interest rate swap, net of tax	(0.6)	(0.4)	0.2	0.7
Ending Balance		0.6	1.5	1.3		1.5
Non-controlling Interest [Member]
Beginning Balance	2.9	2.7	2.8	2.6	2.7	2.6
Net income	0.1	0.1	(0.1)	0.2
Foreign currency translation		0.1	0.1
Purchase of subsidiary shares from noncontrolling interest	2.9		(0.3)
Ending Balance	$ 5.9	$ 2.9	$ 2.5	2.8	$ 5.9	2.5
Unrealized Gain (Loss) on Equity Securities [Member]
Beginning Balance				1.0		$ 1.0
Unrealized Gain (Loss) on Equity Securities [Member] | ASU 2016-01 [Member]
Adoption of accounting principal				$ (1.0)