Summary of Combined Activity Under Equity Incentive Plans (Details) - $ / shares	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Number of Nonqualified Options, Beginning Balance	201,800	159,000	89,700
Granted, Number of Nonqualified Options Outstanding		51,300	69,300
Exercised, Number of Nonqualified Options Outstanding	(7,700)	(4,000)	0
Forfeited, Number of Nonqualified Options Outstanding	(4,000)	(4,500)
Vested, Number of Nonqualified Options Outstanding	0	0	0
Outstanding, Number of Nonqualified Options, Ending Balance	190,100	201,800	159,000
Options, Outstanding, Weighted Average Exercise Price per Share, Beginning Balance	$ 17.47	$ 16.23	$ 17.27
Granted, Weighted Average Exercise Price per Share		21.42	14.87
Exercised, Weighted Average Exercise Price per Share	8.78	8.78
Forfeited, Weighted Average Exercise Price per Share	17.63	26.48
Options, Outstanding, Weighted Average Exercise Price per Share, Ending Balance	17.81	17.47	16.23
Outstanding, Weighted Average Grant-date fair- value per Share, Beginning Balance	28.92	39.98	93.80
Granted, Weighted Average Grant-date fair- value per Share	15.13	21.12	14.84
Forfeited, Weighted Average Grant-date fair- value per Share	18.75	28.73	77.33
Vested, Weighted Average Grant-date fair- value per Share	45.19	22.02	90.73
Outstanding, Weighted Average Grant-date fair- value per Share, Ending Balance	$ 16.42	$ 28.92	$ 39.98
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Number of Restricted Stock Awards, Beginning Balance	288,800	273,650	142,500
Granted, Number of Restricted Stock Awards	176,450	109,500	182,400
Forfeited, Number of Restricted Stock Awards	(21,925)	(3,250)	(2,250)
Vested, Number of Restricted Stock Awards	(116,100)	(91,100)	(49,000)
Options, Number of Restricted Stock Awards, Ending Balance	327,225	288,800	273,650

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

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Number of options vested.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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Number of share options (or share units) exercised during the current period.

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