v3.26.1
INVESTMENTS - Available-for-Sale Debt Securities (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost $ 65,190   $ 65,263      
Allowance for Credit Losses 0 $ 0 0 $ 0 $ 0 $ 0
Gross Unrealized Gains 4,289   4,782      
Gross Unrealized Losses 6,631   5,924      
Fair Value 62,848   64,121      
Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 32,075   32,885      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 497   704      
Gross Unrealized Losses 5,811   5,108      
Fair Value 26,761   28,481      
U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 32,998   32,257      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 3,782   4,068      
Gross Unrealized Losses 820   816      
Fair Value 35,960   35,509      
Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 117   121      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 10   10      
Gross Unrealized Losses 0   0      
Fair Value 127   131      
Japan government and agencies | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 17,381   18,063      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 29   41      
Gross Unrealized Losses 4,047   3,727      
Fair Value 13,363   14,377      
Municipalities            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 1,764   1,930      
Municipalities | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 826   856      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 0   5      
Gross Unrealized Losses 183   145      
Fair Value 643   716      
Municipalities | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 1,085   1,185      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 81   83      
Gross Unrealized Losses 45   54      
Fair Value 1,121   1,214      
Mortgage- and asset-backed securities            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 5,725   4,366      
Mortgage- and asset-backed securities | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 455   297      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 0   1      
Gross Unrealized Losses 51   38      
Fair Value 404   260      
Mortgage- and asset-backed securities | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 5,055   3,854      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 264   239      
Gross Unrealized Losses 45   35      
Fair Value 5,274   4,058      
Mortgage- and asset-backed securities | Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 43   44      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 4   4      
Gross Unrealized Losses 0   0      
Fair Value 47   48      
Public utilities            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 6,954   7,174      
Public utilities | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 2,429   2,519      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 74   123      
Gross Unrealized Losses 225   174      
Fair Value 2,278   2,468      
Public utilities | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 4,297   4,292      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 441   465      
Gross Unrealized Losses 116   107      
Fair Value 4,622   4,650      
Public utilities | Other currencies            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 50   52      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 4   4      
Gross Unrealized Losses 0   0      
Fair Value 54   56      
Sovereign and supranational            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 374   402      
Sovereign and supranational | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 315   330      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 6   7      
Gross Unrealized Losses 22   13      
Fair Value 299   324      
Sovereign and supranational | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 57   57      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 18   21      
Gross Unrealized Losses 0   0      
Fair Value 75   78      
Banks/financial institutions            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 9,218   9,244      
Banks/financial institutions | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 5,298   5,382      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 135   170      
Gross Unrealized Losses 599   477      
Fair Value 4,834   5,075      
Banks/financial institutions | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 3,932   3,672      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 479   518      
Gross Unrealized Losses 27   21      
Fair Value 4,384   4,169      
Other corporate            
Debt Securities, Available-for-sale [Line Items]            
Fair Value 25,246   26,398      
Other corporate | Yen-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 5,371   5,438      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 253   357      
Gross Unrealized Losses 684   534      
Fair Value 4,940   5,261      
Other corporate | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 18,365   18,967      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 2,498   2,740      
Gross Unrealized Losses 583   597      
Fair Value 20,280   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 2   2      
Gross Unrealized Losses 0   0      
Fair Value 26   27      
U.S. government and agencies | U.S. dollar-denominated            
Debt Securities, Available-for-sale [Line Items]            
Amortized Cost 207   230      
Allowance for Credit Losses 0   0      
Gross Unrealized Gains 1   2      
Gross Unrealized Losses 4   2      
Fair Value $ 204   $ 230