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Pensions - Additional Information (Details)
shares in Millions
 12 Months Ended
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
Defined Benefit Plan Disclosure [Line Items]      
Number Of Individuals Elected Lump Sum Settlement 516    
Payments for Repurchase of Common Stock $ 0 $ 37,800,000 $ 10,600,000
Cash dividends paid to stockholders 16,800,000 16,900,000 15,600,000
Amortization of actuarial loss 3,600,000    
Cost of defined contribution pension plans $ 6,900,000 $ 6,900,000 $ 7,500,000
Federal Signal common stock      
Defined Benefit Plan Disclosure [Line Items]      
Company repurchased shares from U.S. benefit plan | shares   0.2  
U.S. Benefit Plans      
Defined Benefit Plan Disclosure [Line Items]      
Weighted-average target return of pension plans 7.10% 7.50% 7.80%
Payments for Repurchase of Common Stock   $ 3,600,000  
Cash dividends paid to stockholders   $ 100,000  
Expected contribution to defined benefit plan $ 5,100,000    
U.S. Benefit Plans | Equity Securities      
Defined Benefit Plan Disclosure [Line Items]      
Minimum target allocation 53.00%    
Maximum target allocation 73.00%    
U.S. Benefit Plans | Fixed Income Securities      
Defined Benefit Plan Disclosure [Line Items]      
Minimum target allocation 25.00%    
Maximum target allocation 45.00%    
U.S. Benefit Plans | Cash and Cash Equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Minimum target allocation 0.00%    
Maximum target allocation 20.00%    
U.S. Benefit Plans | Maximum      
Defined Benefit Plan Disclosure [Line Items]      
Weighted-average target return of pension plans 7.00%    
Non-U.S. Benefit Plan      
Defined Benefit Plan Disclosure [Line Items]      
Weighted-average target return of pension plans 4.20% 4.90% 4.70%
Expected contribution to defined benefit plan $ 1,400,000    
Non-U.S. Benefit Plan | Equity Securities      
Defined Benefit Plan Disclosure [Line Items]      
Minimum target allocation 65.00%    
Maximum target allocation 75.00%    
Non-U.S. Benefit Plan | Debt Securities      
Defined Benefit Plan Disclosure [Line Items]      
Minimum target allocation 25.00%    
Maximum target allocation 35.00%