Business segment data - Earnings data (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Revenues	$ 89,725	$ 89,869
Costs and Expenses:
Interest expense	1,257	1,316
Total costs and expenses	78,268	76,532
Earnings before income taxes	5,148	15,706
BNSF [Member]
Segment Reporting Information [Line Items]
Revenues	5,699	5,637
BHE [Member]
Segment Reporting Information [Line Items]
Revenues	6,344	6,265
Manufacturing [Member]
Segment Reporting Information [Line Items]
Revenues	18,752	18,511
Service and Retailing [Member]
Segment Reporting Information [Line Items]
Revenues	10,112	9,672
Pilot [Member]
Segment Reporting Information [Line Items]
Revenues	10,422	12,494
McLane [Member]
Segment Reporting Information [Line Items]
Revenues	12,016	12,300
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	88,959	89,785
Costs and Expenses:
Interest expense	1,309	1,236
Earnings before income taxes	11,615	12,486
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Revenues	25,375	24,638
Costs and Expenses:
Losses and LAE	14,646	13,448
Life, annuity and health benefits	1,068	945
Other segment items	4,378	3,767
Total costs and expenses	20,092	18,160
Earnings before income taxes	5,283	6,478
Operating Businesses [Member] | Insurance Group [Member] | Underwriting [Member]
Segment Reporting Information [Line Items]
Revenues	21,804	21,474
Costs and Expenses:
Losses and LAE	14,646	13,448
Life, annuity and health benefits	1,068	945
Other segment items	4,368	3,755
Total costs and expenses	20,082	18,148
Earnings before income taxes	1,722	3,326
Operating Businesses [Member] | Insurance Group [Member] | Underwriting [Member] | GEICO [Member]
Segment Reporting Information [Line Items]
Revenues	10,752	10,234
Costs and Expenses:
Losses and LAE	7,424	7,414
Other segment items	1,155	892
Total costs and expenses	8,579	8,306
Earnings before income taxes	2,173	1,928
Operating Businesses [Member] | Insurance Group [Member] | Underwriting [Member] | BH Primary [Member]
Segment Reporting Information [Line Items]
Revenues	4,577	4,541
Costs and Expenses:
Losses and LAE	3,452	2,812
Other segment items	1,269	1,243
Total costs and expenses	4,721	4,055
Earnings before income taxes	(144)	486
Operating Businesses [Member] | Insurance Group [Member] | Underwriting [Member] | BHRG [Member]
Segment Reporting Information [Line Items]
Revenues	6,475	6,699
Costs and Expenses:
Losses and LAE	3,770	3,222
Life, annuity and health benefits	1,068	945
Other segment items	1,944	1,620
Total costs and expenses	6,782	5,787
Earnings before income taxes	(307)	912
Operating Businesses [Member] | Insurance Group [Member] | Investment Income [Member]
Segment Reporting Information [Line Items]
Revenues	3,571	3,164
Costs and Expenses:
Other segment items	10	12
Total costs and expenses	10	12
Earnings before income taxes	3,561	3,152
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Revenues	5,720	5,660
Costs and Expenses:
Compensation and benefits	1,387	1,412
Fuel	770	855
Depreciation and amortization	671	657
Interest expense	272	265
Other segment items	1,017	952
Total costs and expenses	4,117	4,141
Earnings before income taxes	1,603	1,519
Operating Businesses [Member] | BHE [Member]
Segment Reporting Information [Line Items]
Revenues	6,356	6,277
Costs and Expenses:
Energy Cost of Sales	1,531	1,670
Energy Operations and Maintenance	1,249	1,235
Energy Depreciation and Amortization	1,009	982
Real Estate Costs and Expenses	871	1,086
Interest expense	646	645
Other segment items	327	227
Total costs and expenses	5,633	5,845
Earnings before income taxes	723	432
Operating Businesses [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Revenues	18,766	18,529
Costs and Expenses:
Cost of sales and services	12,329	12,232
Cost of leasing	294	243
Interest expense	285	198
Other segment items	3,142	2,942
Total costs and expenses	16,050	15,615
Earnings before income taxes	2,716	2,914
Operating Businesses [Member] | Service and Retailing [Member]
Segment Reporting Information [Line Items]
Revenues	10,137	9,703
Costs and Expenses:
Cost of sales and services	6,064	5,786
Cost of leasing	1,589	1,448
Interest expense	27	29
Other segment items	1,516	1,532
Total costs and expenses	9,196	8,795
Earnings before income taxes	941	908
Operating Businesses [Member] | Pilot [Member]
Segment Reporting Information [Line Items]
Revenues	10,430	12,503
Costs and Expenses:
Cost of sales and services	9,284	11,557
Depreciation and amortization	257	245
Interest expense	72	94
Other segment items	721	631
Total costs and expenses	10,262	12,433
Earnings before income taxes	168	70
Operating Businesses [Member] | McLane [Member]
Segment Reporting Information [Line Items]
Revenues	12,175	12,475
Costs and Expenses:
Cost of sales and services	11,101	11,443
Depreciation and amortization	49	50
Interest expense	7	5
Other segment items	844	817
Total costs and expenses	11,994	12,310
Earnings before income taxes	$ 181	$ 165