NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - COMPONENTS OF COMPERHENSIVE LOSS (Detail) - USD ($)	3 Months Ended												12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 12,866,000	$ 616,000	$ 1,217,000	$ (607,000)	$ 960,000	$ 739,000	$ 582,000	$ (322,000)	$ 955,000	$ 918,000	$ 507,000	$ 146,000	$ 14,092,000	$ 1,959,000	$ 2,526,000
Other comprehensive income:
Foreign currency translation adjustment													208,000	(46,000)	0
Change in unrealized gain (loss) on investments													(19,000)	7,000	5,000
Other comprehensive income													$ 14,281,000	$ 1,920,000	$ 2,531,000