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Line of credit (Detail) - USD ($)
$ in Thousands
1 Months Ended
Nov. 30, 2019
Jan. 31, 2020
Line of Credit Facility [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity $ 5,000  
Line of Credit Oustanding   $ 0
LIBOR Daily Floating Rate    
Line of Credit Facility [Line Items]    
Line of credit, interest rate (as a percent) 2.00%