Business segment data - Additional tabular disclosures (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Interest expense		$ 1,257	$ 1,316
Income tax expense (benefit)		476	2,874
Depreciation and amortization		3,265	3,168
Goodwill	[1]	84,007		$ 83,880	$ 84,626
Assets		1,164,532		1,153,881
Business Segments [Member]
Segment Reporting Information [Line Items]
Interest expense		1,309	1,236
Income tax expense (benefit)		1,939	2,204
Capital expenditures		4,281	4,393
Depreciation and amortization		3,112	3,012
Goodwill		84,007		83,880
Identifiable assets		929,992		932,848
Business Segments [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Income tax expense (benefit)		1,054	1,282
Capital expenditures		24	35
Depreciation and amortization		107	98
Goodwill		16,557		16,557
Identifiable assets		532,016		539,884
Business Segments [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Interest expense		272	265
Income tax expense (benefit)		389	376
Capital expenditures		652	721
Depreciation and amortization		671	657
Goodwill		15,351		15,351
Identifiable assets		81,559		80,813
Business Segments [Member] | Berkshire Hathaway Energy ("BHE") [Member]
Segment Reporting Information [Line Items]
Interest expense		646	645
Income tax expense (benefit)		(422)	(393)
Capital expenditures		2,128	2,153
Depreciation and amortization		1,019	994
Goodwill		11,683		11,669
Identifiable assets		130,643		128,276
Business Segments [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Interest expense		285	198
Income tax expense (benefit)		611	684
Capital expenditures		707	708
Depreciation and amortization		610	601
Goodwill		27,829		27,716
Identifiable assets		120,901		119,860
Business Segments [Member] | Pilot [Member]
Segment Reporting Information [Line Items]
Interest expense		72	94
Income tax expense (benefit)		37	(1)
Capital expenditures		204	172
Depreciation and amortization		257	245
Goodwill		6,477		6,477
Identifiable assets		19,460		19,652
Business Segments [Member] | McLane [Member]
Segment Reporting Information [Line Items]
Interest expense		7	5
Income tax expense (benefit)		45	42
Capital expenditures		22	25
Depreciation and amortization		49	50
Goodwill		232		232
Identifiable assets		7,283		7,165
Business Segments [Member] | Service and Retailing [Member]
Segment Reporting Information [Line Items]
Interest expense		27	29
Income tax expense (benefit)		225	214
Capital expenditures		544	579
Depreciation and amortization		399	367
Goodwill		5,878		5,878
Identifiable assets		38,130		37,198
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment gains (losses), tax		(1,390)	394
Equity method investments, tax		11	88
Goodwill		84,007		83,880
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Interest expense		(52)	80
Income tax expense (benefit)		(84)	188
Depreciation and amortization		153	$ 156
Identifiable assets		$ 150,533		$ 137,153

[1] Net of accumulated goodwill impairments of $11.5 billion as of March 31, 2025 and December 31, 2024 and $11.1 billion as of December 31, 2023.