Revenue from contracts with customers disaggregated by reportable segment and source of revenue (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									$ 166,733	$ 176,512	$ 175,445
Other revenues									78,777	78,104	72,392
Total revenues	$ 64,381	$ 63,024	$ 56,840	$ 61,265	$ 65,368	$ 64,972	$ 63,598	$ 60,678	245,510	254,616	247,837
Industrial and Commercial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,964	25,495	25,911
Building Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,943	15,620	14,323
Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									14,757	14,120	14,790
Grocery and Convenience Store Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									30,795	33,057	33,518
Food and Beverage Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,368	16,767	16,309
Auto Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									8,258	8,481	8,181
Other Retail and Wholesale Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									14,922	14,512	14,158
Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									30,660	33,641	33,304
Electricity and Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,066	14,819	14,951
Manufacturing Businesses [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									55,380	58,992	58,430
Other revenues									3,598	3,632	3,340
Total revenues									58,978	62,624	61,770
Manufacturing Businesses [Member] | Industrial and Commercial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,772	25,311	25,707
Manufacturing Businesses [Member] | Building Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,943	15,620	14,323
Manufacturing Businesses [Member] | Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									14,757	14,120	14,790
Manufacturing Businesses [Member] | Other Retail and Wholesale Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									2,452	2,299	2,091
Manufacturing Businesses [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									1,456	1,642	1,519
McLane Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									46,747	50,363	49,911
Other revenues									93	95	76
Total revenues									46,840	50,458	49,987
McLane Company [Member] | Grocery and Convenience Store Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									30,795	33,057	33,518
McLane Company [Member] | Food and Beverage Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,368	16,767	16,309
McLane Company [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									584	539	84
Service and Retailing Businesses [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									24,252	24,940	24,552
Other revenues									3,859	4,459	4,297
Total revenues									28,111	29,399	28,849
Service and Retailing Businesses [Member] | Industrial and Commercial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									192	184	204
Service and Retailing Businesses [Member] | Auto Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									8,258	8,481	8,181
Service and Retailing Businesses [Member] | Other Retail and Wholesale Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									12,470	12,213	12,067
Service and Retailing Businesses [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									3,332	4,062	4,100
BNSF [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,693	23,302	23,652
Other revenues									57	55	51
Total revenues									20,750	23,357	23,703
BNSF [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,693	23,302	23,652
Berkshire Hathaway Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									19,661	18,915	18,900
Other revenues									1,353	1,181	1,070
Total revenues									21,014	20,096	19,970
Berkshire Hathaway Energy [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									4,595	4,096	3,949
Berkshire Hathaway Energy [Member] | Electricity and Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,066	14,819	14,951
Insurance Corporate And Other [Member]
Disaggregation of Revenue [Line Items]
Other revenues									69,817	68,682	63,558
Total revenues									$ 69,817	$ 68,682	$ 63,558