Business segment data - Revenues (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 61,265	$ 60,678
BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues	5,380	5,725
Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues	4,507	4,672
Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	15,014	15,058
McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues	11,821	12,199
Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	6,938	7,004
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	61,132	60,534
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Interest, dividend and other investment income	1,648	1,487
Total revenues	17,396	15,806
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member]
Segment Reporting Information [Line Items]
Premiums earned	9,109	8,622
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	4,270	3,546
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	2,369	2,151
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues	5,417	5,762
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues	4,507	4,672
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	15,035	15,070
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues	11,821	12,199
Operating Businesses [Member] | Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues	6,956	7,025
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 133	$ 144