Business segment data - Earnings before income taxes (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Investment gains (losses)	$ 23,857	$ 33,061	$ 25,733	$ 67,819
Non-controlled businesses	252	511	745	1,199
Earnings before income taxes	38,137	45,435	53,843	90,187
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	13,302	11,444	25,788	20,984
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	6,915	4,525	13,393	8,112
Investment income	4,068	2,912	7,220	5,297
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	1,786	514	3,714	1,217
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	279	272	765	540
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	782	827	1,694	1,058
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	1,622	1,615	3,141	3,264
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	326	624	758	847
Operating Businesses [Member] | Pilot [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	199	186	269	322
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	3,129	3,103	6,043	5,714
Operating Businesses [Member] | McLane [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	142	129	307	242
Operating Businesses [Member] | Service and Retailing [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	969	1,262	1,877	2,483
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment gains (losses)	23,857	33,061	25,733	67,819
Interest expense, not allocated to segments	(119)	(103)	(215)	(217)
Non-controlled businesses	252	511	745	1,199
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Earnings Before Income Taxes of Operating Businesses	$ 845	$ 522	$ 1,792	$ 402