Revenue Recognition - Disaggregation of Revenue From Contracts With Customers (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2018	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Net sales		$ 269.4	$ 810.1
U.S.
Disaggregation of Revenue [Line Items]
Net sales		215.2	632.5
Canada
Disaggregation of Revenue [Line Items]
Net sales		34.5	112.7
Europe/Other
Disaggregation of Revenue [Line Items]
Net sales		19.7	64.9
Environmental Solutions
Disaggregation of Revenue [Line Items]
Net sales		216.3	646.2
Environmental Solutions | Vehicles and equipment
Disaggregation of Revenue [Line Items]
Net sales	[1]	170.9	511.7
Environmental Solutions | Parts
Disaggregation of Revenue [Line Items]
Net sales		30.0	92.2
Environmental Solutions | Rental income
Disaggregation of Revenue [Line Items]
Net sales	[2]	11.2	30.6
Environmental Solutions | Other
Disaggregation of Revenue [Line Items]
Net sales	[3]	4.2	11.7
Safety and Security Systems
Disaggregation of Revenue [Line Items]
Net sales		53.1	163.9
Safety and Security Systems | Public safety and security equipment
Disaggregation of Revenue [Line Items]
Net sales		29.7	97.0
Safety and Security Systems | Industrial signaling equipment
Disaggregation of Revenue [Line Items]
Net sales		13.2	39.9
Safety and Security Systems | Warning systems
Disaggregation of Revenue [Line Items]
Net sales		$ 10.2	$ 27.0

[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, recognized in accordance with Topic 840.

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