Quarterly report pursuant to Section 13 or 15(d)

Borrowings - Additional Information (Details)

v3.8.0.1
Borrowings - Additional Information (Details) - JP Morgan Chase Bank - Revolving Credit Facility
 3 Months Ended
Mar. 31, 2018
USD ($)
Line of Credit Facility [Line Items]  
Maximum borrowing capacity (up to) $ 30,000,000
Revolving loan payable 0
Amount available under letters of credit 17,064,000
Outstanding letters of credit amount $ 12,261,000
Unused credit commitment fee (percent) 0.25%
Minimum availability required trigger amount (if less than) $ 3,600,000
Number of days below minimum excess availability that triggers cash dominion period 3 days
Number of consecutive days excess availability is above required amount 60 days
Event of default amount $ 0
Excess availability (greater than) 3,600,000
Minimum availability required under availability block $ 2,400,000
Minimum fixed charge ratio if less than minimum excess availability 1.0
Excess availability under credit facility $ 10,324,000
Principal payments due $ 0
One-Month London Interbank Offered Rate (LIBOR)  
Line of Credit Facility [Line Items]  
Applicable margin for LIBOR-based interest rate/ Applicable margin for alternate based rate (percent) 1.75%
Base Rate  
Line of Credit Facility [Line Items]  
Applicable margin for LIBOR-based interest rate/ Applicable margin for alternate based rate (percent) 0.25%
Interest rate (percent) 5.00%
Prime based rate, principal $ 0
London Interbank Offered Rate (LIBOR)  
Line of Credit Facility [Line Items]  
Interest rate (percent) 3.44%
LIBOR based interest rate, principal $ 0