INVESTMENTS - Loan Performance After Modifications (Details) - USD ($) $ in Millions	Mar. 31, 2026	Mar. 31, 2025
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months, nonaccrual	$ 43	$ 20
Current
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	331	443
Less Than 90 Days Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	9	0
90 Days or More Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	43	0
Transitional real estate loans
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months, nonaccrual	43	0
Transitional real estate loans \| Current
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	263	347
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	43	0
Middle market loans
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months, nonaccrual	0	20
Middle market loans \| Current
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	68	96
Middle market loans \| Less Than 90 Days Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	9	0
Middle market loans \| 90 Days or More Past Due
Financing Receivable, Modified, Past Due [Line Items]
Loan modification, after 12 months	$ 0	$ 0