v3.26.1
Investment gains (losses) - Narrative (Detail) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Gain (Loss) on Securities [Line Items]    
Sales of equity securities $ 24,087 $ 4,677
Taxable gains (losses) on sales of equity securities $ 7,200 $ 3,100