Leases - Summary of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Finance lease costs:
Amortization of right of use asset	$ 73	$ 33	$ 214	$ 69
Interest on lease liability	17	2	32	2
Operating lease cost	1,869	1,960	3,940	3,850
Variable lease cost	292	365	470	674
Sublease income	(51)	(55)	(104)	(110)
Total lease cost	$ 2,200	$ 2,305	$ 4,552	$ 4,485

Finance lease costs.

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- Definition

Amount of interest expense on finance lease liability.

+ References

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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

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- Definition

Amount of lease cost recognized by lessee for lease contract.

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

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- Definition

Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

+ References

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