Fair value measurement - Summary of Company's Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Assets
Total financial assets	$ 315,196	$ 378,687
Total financial assets	289,975	443,086
Liabilities
Contingent consideration and indemnity holdback	2,172	11,692
Total financial liabilities	2,172	11,692
U.S. government treasury bills
Assets
Short term investments, fair value	39,126	111,284
Commercial paper
Assets
Short term investments, fair value		14,997
Money market funds
Assets
Total financial assets	217,513	316,805
Corporate bonds
Assets
Total financial assets	33,336
Level 1
Assets
Total financial assets	256,639	428,089
Liabilities
Contingent consideration and indemnity holdback	0	0
Total financial liabilities	0	0
Level 1 | U.S. government treasury bills
Assets
Short term investments, fair value	39,126	111,284
Level 1 | Commercial paper
Assets
Short term investments, fair value		0
Level 1 | Money market funds
Assets
Total financial assets	217,513	316,805
Level 1 | Corporate bonds
Assets
Total financial assets	0
Level 2
Assets
Total financial assets	33,336	14,997
Liabilities
Contingent consideration and indemnity holdback	2,172	9,592
Total financial liabilities	2,172	9,592
Level 2 | U.S. government treasury bills
Assets
Short term investments, fair value	0	0
Level 2 | Commercial paper
Assets
Short term investments, fair value		14,997
Level 2 | Money market funds
Assets
Total financial assets	0	0
Level 2 | Corporate bonds
Assets
Total financial assets	33,336
Level 3
Assets
Total financial assets	0	0
Liabilities
Contingent consideration and indemnity holdback	0	2,100
Total financial liabilities	0	2,100
Level 3 | U.S. government treasury bills
Assets
Short term investments, fair value	0	0
Level 3 | Commercial paper
Assets
Short term investments, fair value		0
Level 3 | Money market funds
Assets
Total financial assets	0	$ 0
Level 3 | Corporate bonds
Assets
Total financial assets	$ 0