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, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 $ 175,445    
Other revenue                 72,392    
Total revenues $ 63,714 $ 63,450 $ 62,200 $ 58,473 $ 58,800 $ 59,507 $ 57,256 $ 64,370 247,837 $ 239,933 $ 215,114
Industrial and Commercial Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 25,911    
Building Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,323    
Consumer Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,790    
Grocery and Convenience Store Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 33,518    
Food and Beverage Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 16,309    
Auto Sales [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 8,181    
Other Retail and Wholesale Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,158    
Service [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 33,304    
Electricity and Natural Gas [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,951    
Manufacturing Businesses [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 58,430    
Other revenue                 3,340    
Total revenues                 61,770    
Manufacturing Businesses [Member] | Industrial and Commercial Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 25,707    
Manufacturing Businesses [Member] | Building Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,323    
Manufacturing Businesses [Member] | Consumer Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,790    
Manufacturing Businesses [Member] | Other Retail and Wholesale Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 2,091    
Manufacturing Businesses [Member] | Service [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 1,519    
McLane Company [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 49,911    
Other revenue                 76    
Total revenues                 49,987    
McLane Company [Member] | Grocery and Convenience Store Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 33,518    
McLane Company [Member] | Food and Beverage Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 16,309    
McLane Company [Member] | Service [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 84    
Service and Retailing Businesses [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 24,552    
Other revenue                 4,297    
Total revenues                 28,849    
Service and Retailing Businesses [Member] | Industrial and Commercial Products [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 204    
Service and Retailing Businesses [Member] | Auto Sales [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 8,181    
Service and Retailing Businesses [Member] | Other Retail and Wholesale Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 12,067    
Service and Retailing Businesses [Member] | Service [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 4,100    
BNSF [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 23,652    
Other revenue                 51    
Total revenues                 23,703    
BNSF [Member] | Service [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 23,652    
Berkshire Hathaway Energy [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 18,900    
Other revenue                 1,070    
Total revenues                 19,970    
Berkshire Hathaway Energy [Member] | Service [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 3,949    
Berkshire Hathaway Energy [Member] | Electricity and Natural Gas [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue from contracts with customers                 14,951    
Insurance Corporate And Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Other revenue                 63,558    
Total revenues                 $ 63,558