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STOCKHOLDERS' EQUITY - Narrative (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2017
Limited Partners' Capital Account [Line Items]
Fair value of stock awards vested	$ 4,979,000
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	0	$ 0
Aggregate intrinsic value of options exercised	296,000
Restricted Stock, Restricted Stock Units And Performance Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	1,515,000	1,390,000
Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	$ 45,000
Restricted Stock | Non Employee Director
Limited Partners' Capital Account [Line Items]
Options, vesting period	3 years
Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	$ 5,148,000
Maximum | Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	$ 7,356,000
Weighted average | Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period	2 years 8 months 12 days
Weighted average | Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period	2 years 3 months 18 days
Weighted average | Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period	2 years 1 month 6 days
2016 Plan
Limited Partners' Capital Account [Line Items]
Options granted, term	10 years
2016 Plan | Minimum
Limited Partners' Capital Account [Line Items]
Options, vesting period	1 year
2016 Plan | Maximum
Limited Partners' Capital Account [Line Items]
Options, vesting period	4 years
Amended and Restated 1997 Employee Stock Purchase Plan
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	$ 47,000	$ 41,000
Class A Common Stock | 2016 Plan
Limited Partners' Capital Account [Line Items]
Common stock, authorized shares			2,250,000
Number of shares available for future grant	1,121,000
Class A Common Stock | 2006 Incentive Plan
Limited Partners' Capital Account [Line Items]
Common stock, additional authorized shares			2,723,000

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