Segment Information - Summary of Net Sales, Operating Income (Loss), and Total Assets by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total net sales	$ 270.1	$ 324.3	$ 556.2	$ 598.1
Total operating income	31.3	46.3	63.6	72.1
Interest expense	1.8	2.0	3.3	4.0
Other expense (income), net	2.0	(0.1)	2.2	0.3
Income before income taxes	27.5	44.4	58.1	67.8
Total assets	1,211.2		1,211.2		$ 1,165.5
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	1,210.9		1,210.9		1,165.2
Discontinued Operations
Segment Reporting Information [Line Items]
Total assets	0.3		0.3		0.3
Environmental Solutions
Segment Reporting Information [Line Items]
Total net sales	214.2	267.2	447.2	486.7
Total operating income	28.6	44.8	58.0	70.5
Environmental Solutions | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	923.8		923.8		908.1
Safety and Security Systems
Segment Reporting Information [Line Items]
Total net sales	55.9	57.1	109.0	111.4
Total operating income	10.4	9.5	17.8	18.2
Safety and Security Systems | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	226.6		226.6		222.6
Corporate And Eliminations
Segment Reporting Information [Line Items]
Total operating income	(7.7)	$ (8.0)	(12.2)	$ (16.6)
Corporate And Eliminations | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	$ 60.5		$ 60.5		$ 34.5