Fair Value of Company's Short-Term Investment and Contingent Consideration by Valuation Hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Current portion contingent consideration liabilities	$ (2,317)
Non-current portion contingent consideration liabilities	(6,932)	$ (10,962)
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	9,900
Current portion contingent consideration liabilities	(2,317)
Non-current portion contingent consideration liabilities	(6,932)	(10,962)
Total contingent consideration liabilities	(9,249)
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	9,900
Fair Value, Measurements, Recurring | Significant Unobservable (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Current portion contingent consideration liabilities	(2,317)
Non-current portion contingent consideration liabilities	(6,932)	$ (10,962)
Total contingent consideration liabilities	(9,249)
Fair Value, Measurements, Recurring | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	9,900
Fair Value, Measurements, Recurring | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 9,900