v3.26.3
INVESTMENTS - Available-for-Sale Debt Securities (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Jun. 30, 2026
Dec. 31, 2025
Sep. 30, 2025
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost $ 65,881   $ 65,263      
Allowance for Credit Losses 0 $ 0 0 $ 0 $ 0 $ 0
Gross Unrealized Gains 2,614   4,782      
Gross Unrealized Losses 7,580   5,924      
Fair Value 60,915   64,121      
Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 31,810   32,885      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 346   704      
Gross Unrealized Losses 5,755   5,108      
Fair Value 26,401   28,481      
U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 33,892   32,257      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 2,266   4,068      
Gross Unrealized Losses 1,821   816      
Fair Value 34,337   35,509      
Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 179   121      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 2   10      
Gross Unrealized Losses 4   0      
Fair Value 177   131      
Japan government and agencies | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 16,808   18,063      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 14   41      
Gross Unrealized Losses 3,634   3,727      
Fair Value 13,188   14,377      
Municipalities            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 1,662   1,930      
Municipalities | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 851   856      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 1   5      
Gross Unrealized Losses 210   145      
Fair Value 642   716      
Municipalities | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 1,086   1,185      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 52   83      
Gross Unrealized Losses 118   54      
Fair Value 1,020   1,214      
Mortgage- and asset-backed securities            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 6,128   4,366      
Mortgage- and asset-backed securities | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 461   297      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 0   1      
Gross Unrealized Losses 62   38      
Fair Value 399   260      
Mortgage- and asset-backed securities | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 5,657   3,854      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 136   239      
Gross Unrealized Losses 166   35      
Fair Value 5,627   4,058      
Mortgage- and asset-backed securities | Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 103   44      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 2   4      
Gross Unrealized Losses 3   0      
Fair Value 102   48      
Public utilities            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 6,582   7,174      
Public utilities | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 2,411   2,519      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 43   123      
Gross Unrealized Losses 279   174      
Fair Value 2,175   2,468      
Public utilities | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 4,370   4,292      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 254   465      
Gross Unrealized Losses 268   107      
Fair Value 4,356   4,650      
Public utilities | Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 52   52      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 0   4      
Gross Unrealized Losses 1   0      
Fair Value 51   56      
Sovereign and supranational            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 372   402      
Sovereign and supranational | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 326   330      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 5   7      
Gross Unrealized Losses 31   13      
Fair Value 300   324      
Sovereign and supranational | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 58   57      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 14   21      
Gross Unrealized Losses 0   0      
Fair Value 72   78      
Banks/financial institutions            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 9,027   9,244      
Banks/financial institutions | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 5,404   5,382      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 111   170      
Gross Unrealized Losses 704   477      
Fair Value 4,811   5,075      
Banks/financial institutions | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 4,055   3,672      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 279   518      
Gross Unrealized Losses 118   21      
Fair Value 4,216   4,169      
Other corporate            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 23,799   26,398      
Other corporate | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 5,549   5,438      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 172   357      
Gross Unrealized Losses 835   534      
Fair Value 4,886   5,261      
Other corporate | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 18,502   18,967      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 1,531   2,740      
Gross Unrealized Losses 1,144   597      
Fair Value 18,889   21,110      
Other corporate | Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 24   25      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 0   2      
Gross Unrealized Losses 0   0      
Fair Value 24   27      
U.S. government and agencies | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 164   230      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 0   2      
Gross Unrealized Losses 7   2      
Fair Value $ 157   $ 230