Notes payable and other borrowings (Detail) (USD $) In Millions, unless otherwise specified					3 Months Ended			3 Months Ended					3 Months Ended			3 Months Ended			3 Months Ended					3 Months Ended			3 Months Ended
	Mar. 31, 2012 Insurance and Other [Member]	Dec. 31, 2011 Insurance and Other [Member]	Mar. 31, 2012 Insurance and Other [Member] Berkshire Hathaway (Parent) [Member]	Dec. 31, 2011 Insurance and Other [Member] Berkshire Hathaway (Parent) [Member]	Mar. 31, 2012 Insurance and Other [Member] Berkshire Hathaway (Parent) [Member] Debt [Member]	Mar. 31, 2012 Insurance and Other [Member] Insurance and Other Subsidiaries [Member]	Dec. 31, 2011 Insurance and Other [Member] Insurance and Other Subsidiaries [Member]	Mar. 31, 2012 Insurance and Other [Member] Insurance and Other Subsidiaries [Member] Debt [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member]	Dec. 31, 2011 Railroad, Utilities and Energy [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member] MidAmerican [Member]	Dec. 31, 2011 Railroad, Utilities and Energy [Member] MidAmerican [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member] MidAmerican [Member] Debt [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member] MidAmerican Subsidiaries [Member]	Dec. 31, 2011 Railroad, Utilities and Energy [Member] MidAmerican Subsidiaries [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member] MidAmerican Subsidiaries [Member] Debt [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member] BNSF [Member]	Dec. 31, 2011 Railroad, Utilities and Energy [Member] BNSF [Member]	Mar. 31, 2012 Railroad, Utilities and Energy [Member] BNSF [Member] Debt [Member]	Mar. 31, 2012 Finance and Financial Products [Member]	Dec. 31, 2011 Finance and Financial Products [Member]	Mar. 31, 2012 Finance and Financial Products [Member] Berkshire Hathaway Finance Corporation [Member]	Dec. 31, 2011 Finance and Financial Products [Member] Berkshire Hathaway Finance Corporation [Member]	Mar. 31, 2012 Finance and Financial Products [Member] Berkshire Hathaway Finance Corporation [Member] Debt [Member]	Mar. 31, 2012 Finance and Financial Products [Member] Other Finance Subsidiaries [Member]	Dec. 31, 2011 Finance and Financial Products [Member] Other Finance Subsidiaries [Member]	Mar. 31, 2012 Finance and Financial Products [Member] Other Finance Subsidiaries [Member] Debt [Member]
Notes payable and other borrowings [Line Items]
Short-term debt, average interest rate						0.20%
Average Interest Rate, percentage			2.30%			5.90%					6.10%			5.40%			5.70%					4.50%			4.80%
Maturity date, range, start					2012			2012					2012			2012			2012					2012			2012
Maturity date, range, end					2047			2035					2037			2042			2097					2040			2036
Short-term borrowings						$ 1,404	$ 1,490
Notes payable and other borrowings	13,635	13,768	8,320	8,287		3,911	3,991		34,523	32,580				15,335	14,552		13,825	12,665		13,677	14,036	11,281	11,531		2,396	2,505
Senior unsecured debt											$ 5,363	$ 5,363