Annual report pursuant to Section 13 and 15(d)

Financings - Additional Information (Detail)

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Financings - Additional Information (Detail) - USD ($)
 1 Months Ended 12 Months Ended
Nov. 16, 2017
Jan. 26, 2017
Feb. 28, 2017
Jul. 31, 2016
Aug. 31, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
May 31, 2016
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           $ 38,633,000 $ 25,993,000    
Weighted average interest rate           4.59% 3.95%    
Interest Expenses           $ 1,800,000 $ 900,000 $ 700,000  
Amortization expense of deferred debt issuance costs               200,000  
Notes payable           2,100,000 14,400,000    
Notes payable, current           1,796,000 2,360,000    
Other Noncurrent Assets                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Deferred debt issuance costs           600,000 200,000    
Amortization expense of deferred debt issuance costs           300,000 200,000    
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      
TNT                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Debt instrument maturity date     Nov. 06, 2017            
Notes payable                 $ 2,000,000
Debt instrument, interest rate                 5.00%
Repayment of notes $ 200,000                
TNT | Maximum                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Interest Expenses           $ 100,000 1,000,000    
TNT | Debt Instrument Due in Twenty Seventeen April Twenty First                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Debt instrument maturity date           Apr. 21, 2017      
Notes payable                 $ 1,000,000
TNT | Debt Instrument Due in Twenty Seventeen November Six                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Debt instrument maturity date           Nov. 06, 2017      
Notes payable                 $ 1,000,000
Energy Source                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Interest Expenses             $ 600,000 $ 200,000  
Repayment of notes   $ 400,000              
Energy Source | Maximum                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Interest Expenses           $ 100,000      
Energy Source | Promissory notes                  
Financing Activities and Borrowing Arrangements [Line Items]                  
Debt instrument maturity date       Jan. 20, 2017 Jul. 20, 2016        
Debt instrument, interest rate       7.00% 5.00%        
Notes payable, current         $ 10,000,000