Segment Information - Summary of Net Sales, Operating Income (Loss), and Total Assets by Segment (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Segment Reporting Information [Line Items]      
Total net sales $ 221.6 $ 200.2  
Total operating income 24.8 12.8  
Interest expense 0.6 1.0  
Other expense, net 0.9 0  
Income before income taxes 23.3 11.8  
Total identifiable assets 649.0   658.7
Discontinued Operations [Member]      
Segment Reporting Information [Line Items]      
Total identifiable assets 4.2   4.2
Continuing Operations [Member]      
Segment Reporting Information [Line Items]      
Total identifiable assets 644.8   654.5
Corporate and Eliminations      
Segment Reporting Information [Line Items]      
Total operating income (6.0) (5.9)  
Total identifiable assets 57.3   68.0
Environmental Solutions      
Segment Reporting Information [Line Items]      
Total net sales 140.2 120.7  
Total operating income 23.9 15.2  
Total identifiable assets 273.6   254.2
Safety And Security Systems      
Segment Reporting Information [Line Items]      
Total net sales 56.3 55.0  
Total operating income 6.6 4.3  
Total identifiable assets 203.6   208.3
Fire Rescue      
Segment Reporting Information [Line Items]      
Total net sales 25.1 24.5  
Total operating income 0.3 (0.8)  
Total identifiable assets $ 110.3   $ 124.0