Debt - Additional Information (Details)
3 Months Ended 9 Months Ended
Apr. 19, 2016
USD ($)
Sep. 26, 2014
USD ($)
Sep. 29, 2017
USD ($)
letters_of_credit
Sep. 30, 2016
USD ($)
Sep. 29, 2017
USD ($)
letters_of_credit
Sep. 30, 2016
USD ($)
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2016
USD ($)
Debt Instrument [Line Items]                  
Debt financing fees     $ 847,000   $ 847,000       $ 1,408,000
Amortization expense         $ 561,000 $ 915,000      
Letters of credit                  
Debt Instrument [Line Items]                  
Credit facility, maximum borrowing capacity $ 35,000,000                
Number of letters of credit outstanding | letters_of_credit     8   8        
Letters of credit outstanding     $ 12,200,000   $ 12,200,000        
Swingline                  
Debt Instrument [Line Items]                  
Credit facility, maximum borrowing capacity 10,000,000                
Senior secured credit facilities                  
Debt Instrument [Line Items]                  
Credit facility, maximum borrowing capacity $ 215,000,000                
Maximum allowed dividend distribution         $ 12,859,794        
Covenant terms, ratio of total indebtedness to combined EBITDA 3.25             3.00  
Covenant terms, ratio of combined EBITDA to combined interest expense         4.50        
Ratio of total indebtedness to combined EBITDA         1.58        
Ratio of combined EBITDA to combined interest expense         10.40        
Interest rate     3.99%   3.99%        
Senior secured credit facilities | Minimum                  
Debt Instrument [Line Items]                  
Undrawn portion of revolving facility, commitment fee percentage         0.40%        
Senior secured credit facilities | Maximum                  
Debt Instrument [Line Items]                  
Undrawn portion of revolving facility, commitment fee percentage         0.50%        
Senior secured credit facilities | London Interbank Offered Rate (LIBOR) | Minimum                  
Debt Instrument [Line Items]                  
Spread on variable rate         2.50%        
Senior secured credit facilities | London Interbank Offered Rate (LIBOR) | Maximum                  
Debt Instrument [Line Items]                  
Spread on variable rate         3.00%        
Term facility                  
Debt Instrument [Line Items]                  
Term facility, amortization rate, year one 7.50%                
Term facility, amortization rate, year two 10.00%                
Term facility, amortization rate, year three 10.00%                
Term facility, amortization rate, year four 15.00%                
Term facility, amortization rate, year five 57.50%                
Balance outstanding under term loan facility     $ 74,500,000   $ 74,500,000        
Term facility | Line of Credit                  
Debt Instrument [Line Items]                  
Credit facility, maximum borrowing capacity $ 140,000,000                
Debt instrument, term 5 years                
Distribution to subsidiary of Exelis   $ 136,300,000              
Debt financing fees   $ 3,700,000              
Amortization expense     200,000 $ 300,000 600,000 $ 900,000      
Revolver | Line of Credit                  
Debt Instrument [Line Items]                  
Credit facility, maximum borrowing capacity $ 75,000,000                
Debt instrument, term 5 years                
Available borrowing capacity     $ 62,800,000   $ 62,800,000        
Forecast | Senior secured credit facilities                  
Debt Instrument [Line Items]                  
Covenant terms, ratio of total indebtedness to combined EBITDA             2.75