v3.25.4
Investments in equity securities (Detail) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Summary of Investment Holdings [Line Items]    
Cost Basis $ 85,389 $ 75,506
Net Unrealized Gains 212,389 196,082
Fair Value 297,778 271,588
Banks, insurance and finance [Member]    
Summary of Investment Holdings [Line Items]    
Cost Basis 15,454 15,707
Net Unrealized Gains 88,675 75,936
Fair Value 104,129 91,643
Consumer products [Member]    
Summary of Investment Holdings [Line Items]    
Cost Basis 11,899 12,658
Net Unrealized Gains 83,055 92,091
Fair Value 94,954 104,749
Commercial, industrial and other [Member]    
Summary of Investment Holdings [Line Items]    
Cost Basis 58,036 47,141
Net Unrealized Gains 40,659 28,055
Fair Value $ 98,695 $ 75,196