Common stock - Narrative (Detail)	3 Months Ended
	Mar. 31, 2025 USD ($) Vote shares	Dec. 31, 2024 shares	Mar. 31, 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%
Treasury shares acquired	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	543,845	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	1,341,567,639	1,335,992,139
Equivalent Class A [Member]
Class of Stock [Line Items]
Shares outstanding	1,438,223	1,438,223