INVESTMENTS - Repurchase Agreements Accounted for as Secured Borrowings (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Total borrowings | $ 6,874 | $ 3,989 |
| Repurchase agreements | ||
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Total borrowings | 240 | $ 0 |
| Japan government and agencies | Repurchase agreements | ||
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Total borrowings | 240 | |
| Maturity four to five years | Repurchase agreements | ||
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Total borrowings | 240 | |
| Maturity four to five years | Japan government and agencies | Repurchase agreements | ||
| Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] | ||
| Total borrowings | $ 240 |