Revenue Recognition - Disaggregation of Revenue From Contracts With Customers (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Net sales	$ 249.7
U.S.
Disaggregation of Revenue [Line Items]
Net sales	196.6
Canada
Disaggregation of Revenue [Line Items]
Net sales	32.4
Europe/Other
Disaggregation of Revenue [Line Items]
Net sales	20.7
Environmental Solutions
Disaggregation of Revenue [Line Items]
Net sales	196.6
Environmental Solutions | Vehicles and equipment
Disaggregation of Revenue [Line Items]
Net sales	155.6	[1]
Environmental Solutions | Parts
Disaggregation of Revenue [Line Items]
Net sales	29.8
Environmental Solutions | Rental income (b)
Disaggregation of Revenue [Line Items]
Net sales	7.8	[2]
Environmental Solutions | Other
Disaggregation of Revenue [Line Items]
Net sales	3.4	[3]
Safety and Security Systems
Disaggregation of Revenue [Line Items]
Net sales	53.1
Safety and Security Systems | Public safety and security equipment
Disaggregation of Revenue [Line Items]
Net sales	30.6
Safety and Security Systems | Industrial signaling equipment
Disaggregation of Revenue [Line Items]
Net sales	13.2
Safety and Security Systems | Warning systems
Disaggregation of Revenue [Line Items]
Net sales	$ 9.3

[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.