STOCK-BASED COMPENSATION - Performance (Details) $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
Mar. 31, 2019 USD ($) tranche $ / shares shares
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance components \| tranche	2
Unrecognized compensation cost (in dollars) \| $	$ 7.5
Weighted average period over which unrecognized compensation cost is expected to be recognized	2 years
Restricted stock awards activity, shares
Granted (in shares) \| shares	145
Outstanding at the end of the period (in shares) \| shares	145
Restricted stock awards activity, weighted average grant date fair value
Granted (in dollars per share) \| $ / shares	$ 62.66
Outstanding at the end of the period (in dollars per share) \| $ / shares	$ 62.66
First Component Of Performance Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance cycle	3 years
Second Component Of Performance Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance cycle	3 years
Number of Tranches \| tranche	3
Sharebased payment award by performance cycle	1 year
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting units ranges	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting units ranges	200.00%

Represents the number of components in performance units award.

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- Definition

Number of tranches in a share based payment arrangement.

+ References

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- Definition

Represents the performance cycle of each tranche in a share based payment arrangement.

+ References

No definition available.

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- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

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- Definition

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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- References

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- Definition

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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- Definition

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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- Definition

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.

+ References

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- Definition

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

+ References

No definition available.

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- Definition

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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- Definition

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.

+ References

No definition available.

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- Definition

Percentage of vesting of share-based compensation awards.

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- Definition

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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