Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Gross number of share options (or share units) granted during the period.

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Stock Award Plans - Narrative (Details) - USD ($)	12 Months Ended
Stock Award Plans - Narrative (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of award (in years)	10 years
Options granted (in shares)	1,043,349	356,343	0
Compensation cost for stock options	$ 1,344,000	$ 521,000	$ 0
Stock Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	1,043,349
Unrecognized compensation cost for stock options, net of forfeitures	$ 3,437,000
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, nonvested (in shares)	409,469	435,838	460,999	466,681
Fair market value at date of grant at restricted stock	$ 9,958,286
Compensation cost for stock options	$ 4,453,000	$ 4,188,000	$ 4,259,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Minimum \| Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	5 years
Maximum \| Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	7 years
2020 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	3,200,000
Shares available for issuance (in shares)	2,546,414