INCOME TAXES - Summary of Valuation Allowance (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2024
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 456	$ 318	$ 227
Balance at End of Period	516	456	318
Charged to Costs and Expenses	$ 60	$ 138	$ 91

Amount of valuation and qualifying accounts and reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column E))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-4

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant