INVESTMENTS - Loan Performance After Modifications (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months, nonaccrual	$ 61	$ 0
Current
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	632	414
Less Than 90 Days Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	11	0
90 Days or More Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	61	0
Transitional real estate loans
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months, nonaccrual	61	0
Transitional real estate loans | Current
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	501	414
Transitional real estate loans | Less Than 90 Days Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	0	0
Transitional real estate loans | 90 Days or More Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	61	$ 0
Middle market loans
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months, nonaccrual	0
Middle market loans | Current
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	131
Middle market loans | Less Than 90 Days Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	11
Middle market loans | 90 Days or More Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	$ 0