Segment Information - Summary of Net Sales, Operating Income (Loss), and Total Assets by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total net sales	$ 249.7	$ 177.8
Total operating income	19.6	11.4
Interest expense	2.5	0.6
Other expense (income), net	0.1	(0.2)
Income before income taxes	17.0	11.0
Total assets	1,008.1		$ 992.3
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,007.6		991.8
Discontinued Operations
Segment Reporting Information [Line Items]
Total assets	0.5		0.5
Environmental Solutions
Segment Reporting Information [Line Items]
Total net sales	196.6	127.8
Total operating income	20.6	10.3
Environmental Solutions | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	768.2		746.4
Safety and Security Systems
Segment Reporting Information [Line Items]
Total net sales	53.1	50.0
Total operating income	6.1	6.4
Safety and Security Systems | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	210.5		211.8
Corporate And Eliminations
Segment Reporting Information [Line Items]
Total operating income	(7.1)	$ (5.3)
Corporate And Eliminations | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	$ 28.9		$ 33.6