Quarterly report pursuant to Section 13 or 15(d)

Revolving Credit Facility and Long-Term Debt - Additional Information (Detail)

v3.8.0.1
Revolving Credit Facility and Long-Term Debt - Additional Information (Detail) - Agreement [Member] - USD ($)
3 Months Ended 9 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Sep. 30, 2017
Dec. 31, 2016
Line of Credit Facility [Line Items]            
Line of credit facility commitment fee description         The Agreement also provides for an unused commitment fee of 0.375% per year on the average daily unused amount of the revolving credit facility, as well as a fee of 1.75% of the face amount of each letter of credit reserved under the line of credit and 0.95% on standalone, fully secured letters of credit.  
Minimum [Member]            
Line of Credit Facility [Line Items]            
EBITDA   $ 25,000,000 $ 25,000,000 $ 25,000,000 $ 25,000,000  
Ratio of restricted and unrestricted cash and marketable securities to workers’ compensation and safety incentive liabilities   100.00% 100.00% 100.00%    
Maximum [Member]            
Line of Credit Facility [Line Items]            
Prohibition on incurring additional indebtedness without the prior approval of the Bank in purchase money financing         $ 1,000,000  
Scenario Forecast [Member] | Minimum [Member]            
Line of Credit Facility [Line Items]            
EBITDA $ 25,000,000          
Ratio of restricted and unrestricted cash and marketable securities to workers’ compensation and safety incentive liabilities 100.00%          
Revolving Credit Facility [Member]            
Line of Credit Facility [Line Items]            
Unused commitment fee on unused amount during period         0.375%  
Outstanding balance on term loan and revolving credit facility   $ 0     $ 0 $ 0
Credit facility, expiration date         Jul. 01, 2018  
Revolving Credit Facility [Member] | Daily Floating Rate [Member]            
Line of Credit Facility [Line Items]            
Term loan from Bank, Interest rate description         A daily floating rate of one month LIBOR plus 1.75%  
LIBOR plus rate         1.75%  
Revolving Credit Facility [Member] | Fixed Rate [Member]            
Line of Credit Facility [Line Items]            
Term loan from Bank, Interest rate description         A fixed rate of LIBOR plus 1.75%  
LIBOR plus rate         1.75%  
Revolving Credit Facility [Member] | Wells Fargo [Member]            
Line of Credit Facility [Line Items]            
Credit facility borrowing capacity   25,000,000     $ 25,000,000  
Standby Letters of Credit [Member]            
Line of Credit Facility [Line Items]            
Credit facility borrowing used   5,900,000     5,900,000  
Standby Letters of Credit [Member] | Wells Fargo [Member]            
Line of Credit Facility [Line Items]            
Credit facility borrowing capacity   6,000,000     $ 6,000,000  
Line of Credit [Member]            
Line of Credit Facility [Line Items]            
Unused commitment fee on unused amount         1.75%  
Fully Secured Letter of Credit [Member]            
Line of Credit Facility [Line Items]            
Unused commitment fee on unused amount         0.95%  
Term Loan [Member]            
Line of Credit Facility [Line Items]            
Term loan from Bank, Interest rate description         One month LIBOR plus 2.00%  
Term loan with principal bank   $ 4,400,000     $ 4,400,000 $ 4,600,000
Payment of monthly principal of term loan         $ 18,375  
Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member]            
Line of Credit Facility [Line Items]            
LIBOR plus rate         2.00%