Marketable Securities - Summary of Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,738	$ 3,168
Fair Value	3,738	3,168
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	20
Fair Value	20
Certificates of Deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	30	51
Fair Value	30	51
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,663	3,101
Fair Value	3,663	3,101
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25
Fair Value	$ 25
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		16
Fair Value		$ 16