REVENUE - TIMING OF REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Timing of Revenue Recognition [Roll Forward]
Customers' credit, beginning	$ 44,910	$ 33,246
Increase (decrease) for customers' credits	(20,032)	(7,725)
Customers' credit, end	24,878	25,521
Billed
Timing of Revenue Recognition [Roll Forward]
Billed, beginning	97,540	222,297
Increase (decrease) for customer accounts receivable	87,529	(27,844)
Billed, end	185,069	194,453
Unbilled
Timing of Revenue Recognition [Roll Forward]
Billed, beginning	19,100	13,769
Increase (decrease) for customer accounts receivable	55,356	32,271
Billed, end	$ 74,456	$ 46,040