Business segment data (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Revenues	$ 51,199	$ 46,541	$ 146,414	$ 135,101
Total earnings before income taxes	6,750	7,378	22,264	21,564
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	51,240	44,466	142,574	130,501
Earnings before income taxes from operating businesses	6,896	5,531	18,742	17,629
Operating Businesses [Member] | Berkshire Hathaway Insurance Group [Member]
Segment Reporting Information [Line Items]
Revenues	13,674	10,354	34,865	31,090
Earnings before income taxes from operating businesses	1,926	1,341	5,722	6,087
Operating Businesses [Member] | Berkshire Hathaway Insurance Group [Member] | Geico [Member]
Segment Reporting Information [Line Items]
Premiums earned	5,203	4,730	15,168	13,726
Earnings before income taxes from operating businesses	264	307	1,010	909
Operating Businesses [Member] | Berkshire Hathaway Insurance Group [Member] | General Re [Member]
Segment Reporting Information [Line Items]
Premiums earned	1,566	1,454	4,733	4,422
Earnings before income taxes from operating businesses	126	63	322	182
Operating Businesses [Member] | Berkshire Hathaway Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	4,809	2,219	8,414	6,918
Earnings before income taxes from operating businesses	443	(206)	617	1,159
Operating Businesses [Member] | Berkshire Hathaway Insurance Group [Member] | Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Premiums earned	1,139	867	3,141	2,396
Earnings before income taxes from operating businesses	143	99	379	228
Operating Businesses [Member] | Berkshire Hathaway Insurance Group [Member] | Investment Income [Member]
Segment Reporting Information [Line Items]
Interest, dividend and other investment income	957	1,084	3,409	3,628
Earnings before income taxes from operating businesses	950	1,078	3,394	3,609
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Revenues	5,881	5,651	17,063	16,257
Earnings before income taxes from operating businesses	1,654	1,556	4,295	4,242
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Revenues	4,853	3,392	13,344	9,564
Earnings before income taxes from operating businesses	1,051	586	2,248	1,574
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Revenues	12,151	11,547	34,327	33,707
Earnings before income taxes from operating businesses	120	126	361	372
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	9,534	8,804	27,788	25,861
Earnings before income taxes from operating businesses	1,337	1,202	3,774	3,301
Operating Businesses [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	3,493	3,179	10,456	9,583
Earnings before income taxes from operating businesses	355	317	1,095	999
Operating Businesses [Member] | Finance and Financial Products Reportable Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,654	1,539	4,731	4,439
Earnings before income taxes from operating businesses	453	403	1,247	1,054
Intersegment Eliminations and Other Reconciling Items [Member]
Segment Reporting Information [Line Items]
Revenues	77	(66)	70	(205)
Investment and derivative gains/losses	(118)	2,141	3,770	4,805
Interest expense	(79)	(80)	(233)	(226)
Earnings before income taxes from operating businesses	$ 51	$ (214)	$ (15)	$ (644)