REVENUE - TIMING OF REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Timing of Revenue Recognition [Roll Forward]
Billed, beginning balance	$ 212,838
Customers' credit, beginning balance	32,586	$ 25,934
Increase for customers' credits balances and deposits	660	6,652
Billed, ending balance	222,297	212,838
Customers' credit, ending balance	33,246	32,586
Billed
Timing of Revenue Recognition [Roll Forward]
Billed, beginning balance	212,838	134,173
Increase for customer accounts receivable	9,459	78,665
Billed, ending balance	222,297	212,838
Unbilled
Timing of Revenue Recognition [Roll Forward]
Billed, beginning balance	10,351	9,226
Increase for customer accounts receivable	3,418	1,125
Billed, ending balance	$ 13,769	$ 10,351