Fair Value of Company's Short-Term Investment and Contingent Consideration by Valuation Hierarchy (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 3,865
Current portion	(2,324)
Non-current portion	(7,720)	$ (10,962)
Total liabilities	(10,044)
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	3,865
Significant Unobservable (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Current portion	(2,324)
Non-current portion	(7,720)	$ (10,962)
Total liabilities	(10,044)
Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	3,865
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	$ 3,865