Leases - Additional information related to leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 5,504	$ 5,223
Operating cash flows from finance leases	1,228	971
Financing cash flows from finance leases	1,757	1,547
Right-of-use assets obtained in exchange for operating lease liabilities	$ 15,609	$ 26,244
Weighted-average remaining lease term
Operating leases	10 years 3 months 18 days	6 years
Finance leases	11 years 8 months 12 days	12 years 6 months
Weighted-average discount rate
Operating leases	3.10%	3.10%
Finance leases	4.20%	4.30%