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GOODWILL AND INTANGIBLE ASSETS - ADDITIONAL INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 34,407	$ 3,014
Disclosure - Goodwill and Intangible Assets - Additional Information (Detail) [Line Items]
Amortization of acquisition-related intangible assets	4,023	591	$ 598
Acquisition-related costs and expenses
Disclosure - Goodwill and Intangible Assets - Additional Information (Detail) [Line Items]
Amortization of acquisition-related intangible assets	$ 4,000	$ 600	$ 600
Minimum
Disclosure - Goodwill and Intangible Assets - Additional Information (Detail) [Line Items]
Estimated useful lives of intangible assets	2 years
Maximum
Disclosure - Goodwill and Intangible Assets - Additional Information (Detail) [Line Items]
Estimated useful lives of intangible assets	7 years

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- References

No definition available.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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