Revenue Recognition - Disaggregation of Revenue From Contracts With Customers (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Net sales		$ 366.7	$ 334.7	$ 696.9	$ 613.5
U.S.
Disaggregation of Revenue [Line Items]
Net sales		299.8	243.7	564.2	459.2
Canada
Disaggregation of Revenue [Line Items]
Net sales		44.0	66.1	86.3	106.7
Europe/Other
Disaggregation of Revenue [Line Items]
Net sales		22.9	24.9	46.4	47.6
Environmental Solutions
Disaggregation of Revenue [Line Items]
Net sales		306.3	281.3	580.5	509.4
Environmental Solutions | Vehicles and equipment
Disaggregation of Revenue [Line Items]
Net sales	[1]	235.8	213.7	453.2	392.7
Environmental Solutions | Parts
Disaggregation of Revenue [Line Items]
Net sales		45.1	39.5	85.9	75.2
Environmental Solutions | Rental income
Disaggregation of Revenue [Line Items]
Net sales	[2]	16.1	13.2	25.8	20.7
Environmental Solutions | Other
Disaggregation of Revenue [Line Items]
Net sales	[3]	9.3	14.9	15.6	20.8
Safety and Security Systems
Disaggregation of Revenue [Line Items]
Net sales		60.4	53.4	116.4	104.1
Safety and Security Systems | Public safety and security equipment
Disaggregation of Revenue [Line Items]
Net sales		37.5	32.1	73.6	63.4
Safety and Security Systems | Industrial signaling equipment
Disaggregation of Revenue [Line Items]
Net sales		15.1	14.3	29.3	27.7
Safety and Security Systems | Warning systems
Disaggregation of Revenue [Line Items]
Net sales		$ 7.8	$ 7.0	$ 13.5	$ 13.0

[1] Includes net sales from the sale of new and used vehicles and equipment, including sales of rental equipment.

[2] Represents income from vehicle and equipment lease arrangements with customers.

[3] Primarily includes revenues from services, such as maintenance and repair work, and the sale of extended warranty contracts.