Notes payable and other borrowings - Narrative (Detail) (USD $)	12 Months Ended											1 Months Ended												1 Months Ended													1 Months Ended								1 Months Ended
	Dec. 31, 2011 Insurance and Other [Member]	Dec. 31, 2010 Insurance and Other [Member]	Dec. 31, 2009 Insurance and Other [Member]	Dec. 31, 2011 Railroad, Utilities and Energy [Member]	Dec. 31, 2010 Railroad, Utilities and Energy [Member]	Dec. 31, 2009 Railroad, Utilities and Energy [Member]	Dec. 31, 2011 Finance and Financial Products [Member]	Dec. 31, 2010 Finance and Financial Products [Member]	Dec. 31, 2009 Finance and Financial Products [Member]	Dec. 31, 2011 Berkshire Hathaway (Parent) [Member]	Dec. 31, 2010 Berkshire Hathaway (Parent) [Member]	Feb. 28, 2010 Berkshire Hathaway (Parent) [Member] Floating Rate Notes Due In 2011 [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Floating Rate Senior Notes Due In 2014 [Member]	Feb. 28, 2010 Berkshire Hathaway (Parent) [Member] Senior Notes [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Senior Notes Due In 2016 at 2.2% [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Senior Notes Due In 2021 at 3.75% [Member]	Jan. 31, 2012 Berkshire Hathaway (Parent) [Member] Senior Notes Due In 2017 at 1.9% [Member] Issuance of Debt [Member]	Jan. 31, 2012 Berkshire Hathaway (Parent) [Member] Senior Notes Due In 2022 at 3.4% [Member] Issuance of Debt [Member]	Feb. 29, 2012 Berkshire Hathaway (Parent) [Member] Floating Rate Notes Due In 2012 [Member] Redemption of Debt [Member]	Feb. 29, 2012 Berkshire Hathaway (Parent) [Member] Notes Due In 2012 at 1.4% [Member] Redemption of Debt [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Debentures [Member]	Dec. 31, 2011 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member]	Dec. 31, 2010 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member]	Feb. 28, 2010 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Unsecured Debt [Member]	Feb. 28, 2011 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Floating Rate Notes Due In 2011 [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Floating Rate Senior Notes Due In 2014 [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Senior Notes [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Senior Notes Due In 2016 at 2.2% [Member]	Aug. 31, 2011 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Senior Notes Due In 2021 at 3.75% [Member]	Jan. 31, 2012 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Senior Notes Due In 2017 at 1.9% [Member] Issuance of Debt [Member]	Jan. 31, 2012 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Senior Notes Due In 2022 at 3.4% [Member] Issuance of Debt [Member]	Feb. 29, 2012 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Floating Rate Notes Due In 2012 [Member] Redemption of Debt [Member]	Feb. 29, 2012 Berkshire Hathaway (Parent) [Member] Insurance and Other [Member] Notes Due In 2012 at 1.4% [Member] Redemption of Debt [Member]	Dec. 31, 2011 Lubrizol Subsidiary [Member] Insurance and Other [Member] Pre-acquisition Debt [Member]	Dec. 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member]	Dec. 31, 2010 BNSF [Member] Railroad, Utilities and Energy [Member]	Aug. 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member] Debentures [Member]	May 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member] Debentures [Member]	May 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member] Debentures Due In June 2021 at 4.1% [Member]	May 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member] Debentures Due In June 2041 at 5.4% [Member]	Aug. 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member] Debentures Due In September 2021 at 3.45% [Member]	Aug. 31, 2011 BNSF [Member] Railroad, Utilities and Energy [Member] Debentures Due In September 2041 at 4.95% [Member]	Dec. 31, 2011 Berkshire Hathaway Finance Corporation [Member] Finance and Financial Products [Member]	Dec. 31, 2010 Berkshire Hathaway Finance Corporation [Member] Finance and Financial Products [Member]	Jan. 31, 2011 Berkshire Hathaway Finance Corporation [Member] Finance and Financial Products [Member] Unsecured Debt [Member]	Jan. 31, 2011 Berkshire Hathaway Finance Corporation [Member] Finance and Financial Products [Member] Floating Rate Senior Notes Due In 2014 [Member]	Jan. 31, 2011 Berkshire Hathaway Finance Corporation [Member] Finance and Financial Products [Member] Unsecured Notes Due In 2021 at 4.25% [Member]	Jan. 31, 2011 Berkshire Hathaway Finance Corporation [Member] Finance and Financial Products [Member] Senior Notes Due In 2014 at 1.5% [Member]	Dec. 31, 2011 Berkshire Hathaway Subsidiaries [Member] Line of Credit and Commercial Paper Facilities [Member]
Debt Instrument [Line Items]
Principal amount of debt issued												$ 2,000,000,000	$ 750,000,000	$ 8,000,000,000	$ 750,000,000	$ 500,000,000	$ 1,100,000,000	$ 600,000,000			$ 2,000,000,000			$ 8,000,000,000		$ 750,000,000	$ 2,000,000,000	$ 750,000,000	$ 500,000,000	$ 1,100,000,000	$ 600,000,000						$ 750,000,000	$ 750,000,000	$ 250,000,000	$ 500,000,000	$ 450,000,000	$ 300,000,000			$ 1,500,000,000	$ 375,000,000	$ 750,000,000	$ 375,000,000
Issuance date																										August 2011	August 2011	August 2011	August 2011	January 2012	January 2012						August 2011	May 2011	May 2011	May 2011	August 2011	August 2011			January 2011	January 2011	January 2011	January 2011
Debt Instrument, Interest Rate, Stated Percentage																												2.20%	3.75%										4.10%	5.40%	3.45%	4.95%					4.25%	1.50%
Repayment of debt	2,307,000,000	430,000,000	746,000,000	2,335,000,000	777,000,000	444,000,000	1,959,000,000	2,417,000,000	396,000,000										1,100,000,000	600,000,000					2,000,000,000							1,100,000,000	600,000,000												1,500,000,000
Notes payable and other borrowings	13,768,000,000	12,471,000,000		32,580,000,000	31,626,000,000		14,036,000,000	14,477,000,000		8,287,000,000	8,360,000,000											8,287,000,000	8,360,000,000											1,600,000,000	12,665,000,000	11,980,000,000							11,531,000,000	11,535,000,000
Unused lines of credit available																																																	$ 3,700,000,000