INCOME TAXES - Differences Between Federal Income Tax Rate and Effective Income Tax Rate (Details)	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Statutory federal tax	21.00%	21.00%	21.00%
Adjustments to reconcile to the effective income tax rate:
State income taxes	1.00%	2.00%	3.00%
Stock-based compensation	(5.00%)	(2.00%)	(1.00%)
Foreign rate differential	(8.00%)	0.00%	0.00%
Disallowed loss on sale of business	(23.00%)	0.00%	0.00%
Solar tax credits	0.00%	0.00%	(5.00%)
General business credits	0.05	0	0
Nondeductible executive compensation	(11.00%)	1.00%	0.00%
Nondeductible goodwill	(16.00%)	0.00%	0.00%
Pillar 2 Income Taxes	(1.00%)	0.00%	0.00%
Foreign-derived intangible income	1.00%	0.00%	0.00%
Non-deductible meals & entertainment	(2.00%)	0.00%	0.00%
Changes in valuation allowances	1.00%	0.00%	0.00%
Changes in reserves for uncertain tax positions	(0.07)	0	0
Nontaxable solar tax credits	66.00%	(3.00%)	0.00%
Return to provision	(2.00%)	0.00%	0.00%
Other	(2.00%)	0.00%	1.00%
Effective income tax rate	18.00%	19.00%	19.00%