Quarterly report pursuant to Section 13 or 15(d)

Credit Facilities - Additional Information (Details)

v3.20.1
Credit Facilities - Additional Information (Details)
3 Months Ended
Feb. 28, 2020
Mar. 31, 2020
USD ($)
Apr. 17, 2020
USD ($)
Line of Credit Facility [Line Items]      
Revolving credit facility   $ 40,000,000  
Financial covenants, minimum current assets to current liabilities ratio   1.25  
Financial covenants, minimum net worth   $ 130,000,000  
Debt instrument, covenant terms percent of proceeds from stock issuance added to net worth requirement (percentage)   100.00%  
Cash, cash equivalents, and short-term investments   $ 68,600,000  
Financial covenant, maximum funded debt to tangible net worth ratio   0.50  
Outstanding borrowings under our Credit Agreement   $ 0  
Total outstanding letters of credit   9,800,000  
Remaining borrowing capacity on line of credit   30,200,000  
Tangible net worth   $ 159,300,000  
Current ratio   1.80  
Funded debt to tangible net worth ratio   0.06  
Surety bonds   $ 411,800,000  
Letter of Credit      
Line of Credit Facility [Line Items]      
Stated interest rate (percentage) 2.00%    
Letter of Credit | Prime Rate      
Line of Credit Facility [Line Items]      
Basis spread on variable rate (percentage)   3.30%  
Letter of Credit | London Interbank Offered Rate (LIBOR)      
Line of Credit Facility [Line Items]      
Basis spread on variable rate (percentage) 2.00% 1.00%  
Revolving Credit Facility      
Line of Credit Facility [Line Items]      
Fees on undrawn borrowings (percentage) 0.40%    
PPP Loan | Subsequent Event      
Line of Credit Facility [Line Items]      
Stated interest rate (percentage)     1.00%
Unsecured loan amount     $ 10,000,000
Minimum      
Line of Credit Facility [Line Items]      
Cash, cash equivalents, and short-term investments   $ 40,000,000