Quarterly report pursuant to Section 13 or 15(d)

Financings - Additional Information (Detail)

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Financings - Additional Information (Detail) - USD ($)
 3 Months Ended
Jan. 26, 2017
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Financing Activities and Borrowing Arrangements [Line Items]        
Line of credit facility, maximum borrowing amount $ 50,000,000      
Line of credit facility, maturity date Jan. 26, 2020      
Guaranteed borrowing capacity   $ 10,000,000    
Revolving credit facility   40,060,000   $ 38,633,000
Interest Expenses   500,000 $ 400,000  
Amortization expense of deferred debt issuance costs     $ 100,000  
Other Noncurrent Assets        
Financing Activities and Borrowing Arrangements [Line Items]        
Deferred debt issuance costs   500,000   $ 600,000
Amortization expense of deferred debt issuance costs   100,000    
London Interbank Offered Rate (LIBOR)        
Financing Activities and Borrowing Arrangements [Line Items]        
Debt instrument, basis spread on variable rate 2.75%      
Base Rate        
Financing Activities and Borrowing Arrangements [Line Items]        
Debt instrument, basis spread on variable rate 1.75%      
Value Lighting        
Financing Activities and Borrowing Arrangements [Line Items]        
Debt refinance amount   3,700,000    
Value Lighting | Debt Instrument Due in Twenty Eighteen November Twenty Two        
Financing Activities and Borrowing Arrangements [Line Items]        
Lump sum payment   $ 1,400,000    
Debt instrument maturity date   Nov. 22, 2018