Business segment data - Revenues (Detail) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment Reporting Information [Line Items]
Revenues	$ 37,052	$ 33,319	$ 70,775	$ 63,427
Reconciliation of segments to consolidated amount:
Total revenues	38,274	31,709	71,994	63,746
Geico [Member]
Segment Reporting Information [Line Items]
Premiums earned	3,818	3,554	7,493	7,008
General Re [Member]
Segment Reporting Information [Line Items]
Premiums earned	1,444	1,373	2,881	2,813
Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	3,268	1,546	5,212	3,653
Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	419	391	845	816
Insurance Group [Member]
Segment Reporting Information [Line Items]
Investment income	1,410	1,500	2,676	2,802
Revenues	10,359	8,364	19,107	17,092
Burlington Northern Santa Fe [Member]
Segment Reporting Information [Line Items]
Revenues	4,790	4,094	9,323	6,167	[1]
Finance and Financial Products [Member]
Segment Reporting Information [Line Items]
Revenues	991	1,149	1,904	2,126
Reconciliation of segments to consolidated amount:
Total revenues	967	(1,026)	2,163	394
Marmon [Member]
Segment Reporting Information [Line Items]
Revenues	1,781	1,562	3,455	2,959
McLane Company [Member]
Segment Reporting Information [Line Items]
Revenues	8,444	8,293	16,211	15,723
MidAmerican [Member]
Segment Reporting Information [Line Items]
Revenues	2,678	2,672	5,558	5,649
Other Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	8,009	7,185	15,217	13,711
Investment and derivative gain / loss [Member]
Reconciliation of segments to consolidated amount:
Total revenues	1,105	(1,793)	969	(64)
Eliminations and other [Member]
Reconciliation of segments to consolidated amount:
Total revenues	$ 117	$ 183	$ 250	$ 383

[1] Includes revenues and earnings from February 13, 2010.