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Debt - Additional Information (Detail)
Jun. 29, 2018
USD ($)
Financial_Institution
Mar. 16, 2020
USD ($)
Jan. 31, 2020
USD ($)
Line of Credit Facility [Line Items]      
Line of credit outstanding     $ 0
COVID 19 Outbreak | Subsequent Event      
Line of Credit Facility [Line Items]      
Line of credit outstanding   $ 220,000,000  
Stand-by letters of credit      
Line of Credit Facility [Line Items]      
Letter of credit outstanding     14,071,000
Trade Letter of Credit      
Line of Credit Facility [Line Items]      
Letter of credit outstanding     62,155,000
Number of financial institutions with borrowing agreements | Financial_Institution 2    
Line of credit facility available for purposes of trade of letter of credit $ 130,000,000    
Line of credit facility, available amount     $ 67,845,000
JPMorgan Chase Bank N. A. | Revolving Credit Facility      
Line of Credit Facility [Line Items]      
Credit agreement initiation date Jun. 29, 2018    
Credit facility maturity date 2023-06    
Credit facility maximum borrowing capacity $ 350,000,000    
Additional line of credit facility $ 150,000,000    
Commitment fee percentage 0.20%    
JPMorgan Chase Bank N. A. | Revolving Credit Facility | Adjusted LIBOR, CDOR or EURIBOR | Minimum      
Line of Credit Facility [Line Items]      
Applicable margin 1.125%    
JPMorgan Chase Bank N. A. | Revolving Credit Facility | Adjusted LIBOR, CDOR or EURIBOR | Maximum      
Line of Credit Facility [Line Items]      
Applicable margin 1.375%    
JPMorgan Chase Bank N. A. | Revolving Credit Facility | Adjusted ABR | Minimum      
Line of Credit Facility [Line Items]      
Applicable margin 0.125%    
JPMorgan Chase Bank N. A. | Revolving Credit Facility | Adjusted ABR | Maximum      
Line of Credit Facility [Line Items]      
Applicable margin 0.375%