OTHER COMPREHENSIVE INCOME (LOSS) - Total comprehensive income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net income	$ 79,211	$ 53,429	$ 37,287
Other comprehensive income (loss), net of taxes	26,115	(6,176)	(31,804)
Comprehensive income	$ 105,326	$ 47,253	$ 5,483