v3.25.2
Investments in equity securities (Detail) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Summary of Investment Holdings [Line Items]    
Cost Basis $ 79,398 $ 75,506
Net Unrealized Gains 188,525 196,082
Fair Value 267,923 271,588
Banks, insurance and finance [Member]    
Summary of Investment Holdings [Line Items]    
Cost Basis 14,080 15,707
Net Unrealized Gains 79,344 75,936
Fair Value 93,424 91,643
Consumer products [Member]    
Summary of Investment Holdings [Line Items]    
Cost Basis 13,418 12,658
Net Unrealized Gains 78,057 92,091
Fair Value 91,475 104,749
Commercial, industrial and other [Member]    
Summary of Investment Holdings [Line Items]    
Cost Basis 51,900 47,141
Net Unrealized Gains 31,124 28,055
Fair Value $ 83,024 $ 75,196