Selected Quarterly Financial Data - Summary of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 196.2	$ 222.0	$ 223.4	$ 198.0	$ 179.2	$ 199.6	$ 198.7	$ 175.7	$ 839.6	$ 753.2
Gross margin	38.1	44.6	45.1	38.7	36.8	41.3	42.2	35.5	166.5	155.8	$ 151.2
Operating expenses	44.2	41.1	43.0	39.2	42.4	38.2	38.1	37.0	167.5	155.7	128.5
Operating income (loss)	(6.0)	3.5	2.1	(0.5)	(5.6)	3.1	4.1	(1.5)	(0.9)	0.1	22.7
Net income (loss) from continuing operations	(6.9)	$ 1.2	$ 0.2	$ (0.5)	(8.9)	1.3	2.3	$ (0.9)	(6.0)	(6.2)	13.3
Net income (loss) from discontinued operations	$ (0.4)				$ (0.9)	$ 0.1	$ (0.1)		$ (0.4)	$ (0.9)	$ 3.0
Net income (loss) from continuing operations	$ (0.27)	$ 0.05	$ 0.01	$ (0.02)	$ (0.36)	$ 0.05	$ 0.09	$ (0.04)	$ (0.24)	$ (0.25)	$ 0.52
Net income (loss) from discontinued operations	(0.02)				(0.03)				(0.02)	(0.04)	0.12
Net income (loss)	$ (0.29)	$ 0.05	$ 0.01	$ (0.02)	$ (0.39)	$ 0.05	$ 0.09	$ (0.04)	$ (0.26)	$ (0.29)	$ 0.64

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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