EQUITY-BASED INCENTIVE AWARDS - Stock Options (Details) $ / shares in Units, $ in Millions	12 Months Ended
Sep. 30, 2018 USD ($) item $ / shares shares	Sep. 30, 2017 USD ($) $ / shares shares
Omnibus plan and stock option activity
Number of incentive plans \| item	2
Stock options issued and outstanding
Number Outstanding (in shares)	33,800
Weighted-Average Exercise Price (in dollars per share) \| $ / shares	$ 77.85
Stock Options
Omnibus plan and stock option activity
Vesting period	5 years	5 years
Estimated fair value of the stock option awards using the Black-Scholes option pricing model \| $	$ 0.2	$ 0.1
Expiration period	10 years	10 years
Stock Option Pricing Assumptions
Risk-free interest rate (as a percent)	2.41%	2.12%
Dividend yield (as a percent)	0.80%	0.60%
Expected volatility (as a percent)	33.00%	22.40%
Expected life	6 years	6 years
Stock options issued and outstanding
Number Outstanding (in shares)	33,800	28,300
Weighted-Average Exercise Price (in dollars per share) \| $ / shares	$ 77.85	$ 74.75
Number Exercisable (in shares)	17,300
Exercisable, Weighted-Average Exercise Price (in dollars per share) \| $ / shares	$ 68.04
Number of Shares
Granted (in shares)	6,000	6,000
Exercised (in shares)	(500)
Weighted Average Exercise Price
Granted (in dollars per share) \| $ / shares	$ 90.50
Exercised (in dollars per share) \| $ / shares	$ 96.50
Aggregate intrinsic value and fair value of options outstanding
Compensation expense related to the amortization of all equity - based compensation awards \| $	$ 0.1	$ 0.1
Total unamortized compensation expense \| $	$ 0.2
Amortization period of unamortized compensation expense	29 months
Aggregate intrinsic value of options outstanding \| $	$ 0.4	0.5
Aggregate intrinsic value of options exercisable \| $	0.3	0.4
Total intrinsic value of options \| $	0.1	0.1
Total fair value of options vested \| $	$ 0.4	$ 0.4
Omnibus Plan
Omnibus plan and stock option activity
Number of shares of the company's common stock permitted for issuance under the plan	225,000
Number of shares awarded pursuant to the plan	208,095
Number of additional shares that may be awarded under the plan	5,068

Represents the number of share based incentive plans during the period.

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Represents the grant-date fair value of options granted during the reporting period as calculated by applying the Black-Scholes option pricing methodology.

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Number of share instruments newly issued at the reporting date under a share-based compensation plan, net of forfeitures.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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 maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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

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