Debt - Additional Information (Details)
3 Months Ended
Nov. 15, 2017
USD ($)
Mar. 30, 2018
USD ($)
letters_of_credit
Mar. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
Debt Instrument [Line Items]        
Debt financing fees   $ 1,683,000   $ 1,789,000
Amortization expense   $ 106,000 $ 194,000  
Letters of credit        
Debt Instrument [Line Items]        
Credit facility, maximum borrowing capacity $ 25,000,000      
Number of letters of credit outstanding | letters_of_credit   7    
Letters of credit outstanding   $ 10,200,000    
Senior secured credit facilities        
Debt Instrument [Line Items]        
Credit facility, maximum borrowing capacity $ 200,000,000      
Maximum allowed dividend distribution   $ 10,000,000    
Covenant terms, ratio of total indebtedness to combined EBITDA   3.00    
Covenant terms, maximum debt to EBITDA ratio, twelve months following purchase   3.25    
Covenant terms, ratio of EBITDA to interest expense, net,   4.50    
Ratio of total indebtedness to combined EBITDA   1.48    
Ratio of combined EBITDA to combined interest expense   11.04    
Interest rate   4.13%    
Senior secured credit facilities | Minimum        
Debt Instrument [Line Items]        
Undrawn portion of revolving facility, commitment fee percentage   0.30%    
Senior secured credit facilities | Maximum        
Debt Instrument [Line Items]        
Undrawn portion of revolving facility, commitment fee percentage   0.45%    
Senior secured credit facilities | London Interbank Offered Rate (LIBOR) | Minimum        
Debt Instrument [Line Items]        
Spread on variable rate   1.75%    
Senior secured credit facilities | London Interbank Offered Rate (LIBOR) | Maximum        
Debt Instrument [Line Items]        
Spread on variable rate   2.50%    
Senior secured credit facilities | Base Rate | Minimum        
Debt Instrument [Line Items]        
Spread on variable rate   0.75%    
Senior secured credit facilities | Base Rate | Maximum        
Debt Instrument [Line Items]        
Spread on variable rate   1.50%    
Term facility        
Debt Instrument [Line Items]        
Term facility, amortization rate, year one 100000000.00%      
Term facility, amortization rate, year two 150000000.00%      
Term facility, amortization rate, year three 200000000.00%      
Term facility, amortization rate, year four 260000000.00%      
Term facility, amortization rate, year five 4760000000.00%      
Balance outstanding under term loan facility   $ 78,000,000    
Term facility | Line of Credit        
Debt Instrument [Line Items]        
Credit facility, maximum borrowing capacity $ 80,000,000      
Debt instrument, term 5 years      
Distribution to subsidiary of Exelis   74,600,000    
Debt financing fees   1,800,000    
Amortization expense   100,000 $ 200,000  
Revolver | Line of Credit        
Debt Instrument [Line Items]        
Credit facility, maximum borrowing capacity $ 120,000,000      
Debt instrument, term 5 years      
Available borrowing capacity   $ 109,800,000