COMMITMENTS, CONTINGENCIES AND GUARANTEES, Commitments Narrative (Details) $ in Millions	6 Months Ended
	Mar. 31, 2024 USD ($) commitment
Commitments [Line Items]
Amount of commitment	$ 27
Underwriting commitment
Commitments [Line Items]
Number of open underwriting commitments | commitment	2
Investment commitment
Commitments [Line Items]
Amount of commitment	$ 61
Commitment to lend to RJTCF
Commitments [Line Items]
Amount of commitment	$ 199
Number of days that investments in project partnerships are typically sold (in days)	90 days