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INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Taxes [Line Items]
Amount of foreign net operating loss carryforwards		$ 88.9
Equity compensation		5.7
Accrued interest and penalties related to unrecognized tax benefits		3.4	$ 0.6	$ 2.9
Potential increase (decrease) in uncertain tax liabilities		23.9
Forecast
Income Taxes [Line Items]
Potential increase (decrease) in uncertain tax liabilities	$ (6.9)
Domestic | Research Tax Credit Carryforward
Income Taxes [Line Items]
Amount of net operating loss carryforwards		0.3
State
Income Taxes [Line Items]
Amount of net operating loss carryforwards		18.7
Foreign
Income Taxes [Line Items]
Amount of net operating loss carryforwards		429.6
Deferred tax assets, net		129.6
Foreign | Foreign Interest Expense
Income Taxes [Line Items]
Amount of net operating loss carryforwards		$ 194.4

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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-Topic 740
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