Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurement - Summary of Contractual Maturities of Available for Sale Securities (Detail)

v3.21.1
Fair Value Measurement - Summary of Contractual Maturities of Available for Sale Securities (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Sep. 30, 2020
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year $ 138,534 $ 86,186
Available for sale securities, contractual maturities between 1 to 5 years 81,754 87,596
Available for sale securities, contractual maturities between 5 to 10 years 56,462 151,042
Available for sale securities, contractual maturities after 10 years 36,793 34,793
Available for sale securities, contractual maturities, Total 313,543 359,617
Corporate Bonds [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year 49,308 44,701
Available for sale securities, contractual maturities between 1 to 5 years 61,315 68,171
Available for sale securities, contractual maturities between 5 to 10 years 34,172 95,969
Available for sale securities, contractual maturities, Total 144,795 208,841
Money Market Funds [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year 82,066 39,519
Available for sale securities, contractual maturities, Total 82,066 39,519
U.S. Government Agency Securities [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year 1,013 1,007
Available for sale securities, contractual maturities between 1 to 5 years 18,668 18,497
Available for sale securities, contractual maturities between 5 to 10 years 20,670 25,181
Available for sale securities, contractual maturities, Total 40,351 44,685
Asset Backed Securities [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year 2  
Available for sale securities, contractual maturities between 1 to 5 years 267 246
Available for sale securities, contractual maturities between 5 to 10 years   2,201
Available for sale securities, contractual maturities after 10 years 36,793 34,793
Available for sale securities, contractual maturities, Total 37,062 37,240
U.S. Treasuries [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year 1,367 959
Available for sale securities, contractual maturities between 1 to 5 years 1,504 682
Available for sale securities, contractual maturities between 5 to 10 years 1,620 27,691
Available for sale securities, contractual maturities, Total 4,491 $ 29,332
Supranational Bonds [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available for sale securities, contractual maturities less than 1 year 4,778  
Available for sale securities, contractual maturities, Total $ 4,778