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Investments (Tables)
3 Months Ended
Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]  
Schedule of Held-to-Maturity Investments
The amortized cost, gross unrealized gains or losses, and fair value of investments classified as held-to-maturity at December 31, 2020 were as follows:
Gross UnrealizedEstimated Fair
Due in less than 1 year:Amortized CostGainsLossesMarket Value
   Corporate and municipal bonds$27,878 $— $(20)$27,858 
Total as of December 31, 2020$27,878 $— $(20)$27,858