v3.25.2
Common stock - Narrative (Detail)
 6 Months Ended
Jun. 30, 2025
USD ($)
Vote
shares
Dec. 31, 2024
shares
Jun. 30, 2024
Class of Stock [Line Items]      
Preferred Stock, shares authorized 1,000,000    
Preferred Stock, shares issued 0    
Economic equivalent of Class B share to Class A share 0.0667%   0.0667%
Share repurchases 0    
Common Stock Repurchase Program [Member]      
Class of Stock [Line Items]      
Shares repurchase, authorization description Berkshire’s common stock repurchase program permits Berkshire to repurchase its shares any time that Warren Buffett, Berkshire’s Chairman of the Board and Chief Executive Officer, believes that the repurchase price is below Berkshire’s intrinsic value, conservatively determined.    
Minimum cash, cash equivalents and U.S. Treasury Bill threshold after repurchase of common stock shares, amount | $ $ 30,000,000,000    
Class A [Member]      
Class of Stock [Line Items]      
Number of votes entitled per share, number | Vote 1    
Shares outstanding 531,469 547,562  
Class B [Member]      
Class of Stock [Line Items]      
Number of votes entitled per share, number | Vote 0.0001    
Number of shares of Class B stock obtainable from converting one Class A share 1,500    
Shares outstanding 1,360,131,639 1,335,992,139  
Equivalent Class A [Member]      
Class of Stock [Line Items]      
Shares outstanding 1,438,223 1,438,223