Business segment data - Revenues (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 56,840	$ 63,598	$ 118,105	$ 124,276
BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues	4,572	5,851	9,952	11,576
Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues	4,659	4,970	9,166	9,642
Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	13,017	16,191	28,031	31,250
McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues	11,218	12,411	23,039	24,610
Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	6,021	7,440	12,959	14,443
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	56,759	63,459	117,891	123,993
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Interest, dividend and other investment income	1,615	1,654	3,263	3,141
Total revenues	17,210	16,517	34,606	32,323
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member]
Segment Reporting Information [Line Items]
Premiums earned	9,040	8,869	18,149	17,491
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	4,311	3,707	8,581	7,253
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	2,244	2,287	4,613	4,438
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues	4,602	5,893	10,019	11,655
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues	4,659	4,970	9,166	9,642
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	13,033	16,206	28,068	31,276
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues	11,218	12,411	23,039	24,610
Operating Businesses [Member] | Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	6,037	7,462	12,993	14,487
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 81	$ 139	$ 214	$ 283