Leases - Lease Cost (Details) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)
Leases [Abstract]
Operating lease cost	$ 6,518	$ 11,926
Finance lease cost, depreciation of lease assets	811	1,268
Finance lease cost, interest on lease liabilities	89	148
Short-term lease cost	(256)	807
Variable lease cost	846	1,820
Total lease cost	$ 8,008	$ 15,969
Operating leases, weighted average remaining lease term (in months)	68 months	68 months
Operating leases, weighted average discount rate	3.85%	3.85%
Finance leases, weighted average remaining lease term (in months)	32 months	32 months
Finance leases, weighted average discount rate	3.87%	3.87%

Amount of interest expense on finance lease liability.

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-Name Accounting Standards Codification
-Topic 842
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-Section 50
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Amount of amortization expense attributable to right-of-use asset from finance lease.

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Weighted average discount rate for finance lease calculated at point in time.

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Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of lease cost recognized by lessee for lease contract.

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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.

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Weighted average discount rate for operating lease calculated at point in time.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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

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