Business segment data - Revenues (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 64,972	$ 63,450	$ 189,248	$ 184,123
BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues	5,982	6,112	17,558	17,547
Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues	5,720	5,706	15,362	15,268
Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	15,881	15,665	47,130	46,274
McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues	12,604	12,822	37,214	37,438
Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	7,354	7,211	21,798	21,284
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	64,732	63,370	188,725	183,955
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Interest, dividend and other investment income	1,789	1,446	4,930	4,058
Total revenues	17,112	15,779	49,435	45,913
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member]
Segment Reporting Information [Line Items]
Premiums earned	8,996	8,506	26,487	24,705
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	3,940	3,777	11,193	11,229
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	2,387	2,050	6,825	5,921
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues	6,021	6,147	17,676	17,649
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues	5,720	5,706	15,362	15,268
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	15,897	15,686	47,173	46,335
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues	12,604	12,822	37,214	37,438
Operating Businesses [Member] | Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	7,378	7,230	21,865	21,352
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 240	$ 80	$ 523	$ 168