Segment Information - Summary of Net Sales, Operating Income (Loss), and Total Assets by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total net sales	$ 278.8	$ 286.1
Total operating income	27.8	32.3
Interest expense	1.1	1.5
Other (income) expense, net	(0.5)	0.2
Income before income taxes	27.2	30.6
Total assets	1,266.1		$ 1,208.8
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,265.9		1,208.6
Discontinued Operations
Segment Reporting Information [Line Items]
Total assets	0.2		0.2
Environmental Solutions
Segment Reporting Information [Line Items]
Total net sales	228.1	233.0
Total operating income	27.1	29.4
Environmental Solutions | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,013.0		926.8
Safety and Security Systems
Segment Reporting Information [Line Items]
Total net sales	50.7	53.1
Total operating income	7.2	7.4
Safety and Security Systems | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	222.0		225.5
Corporate And Eliminations
Segment Reporting Information [Line Items]
Total operating income	(6.5)	$ (4.5)
Corporate And Eliminations | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	$ 30.9		$ 56.3