Fair value measurement - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Dec. 31, 2022	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration (in shares)		104,727
Company common stock		$ 1,800
Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability value				$ 0	$ 7,193
Change in fair value	$ (2,100)			(5,426)
Equity securities, FV-NI, amortized cost			$ 1,525	3,711
Equity ownership, excluding consolidated entity and equity method investee, percentage			15.00%
Equity securities, FV-NI, current			$ 1,500
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability value			0	0	$ 2,100
Change in fair value				$ (2,100)
Equity Method Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment			2,186
Convertible Note | Convertible Notes Payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, FV-NI, amortized cost			$ 3,500
Debt instrument, interest rate, stated percentage			4.00%