Notes payable and other borrowings - Narrative (Detail) (USD $)	6 Months Ended							1 Months Ended	6 Months Ended			1 Months Ended	6 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended		1 Months Ended			1 Months Ended		6 Months Ended	1 Months Ended		1 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended		1 Months Ended
	Jun. 30, 2013 Insurance and Other [Member]	Jun. 30, 2012 Insurance and Other [Member]	Jun. 30, 2013 Railroad, Utilities and Energy [Member]	Jun. 30, 2012 Railroad, Utilities and Energy [Member]	Jun. 30, 2013 Finance and Financial Products [Member]	Jun. 30, 2012 Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway (Parent) [Member] Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]	Jan. 31, 2013 Berkshire Hathaway (Parent) [Member] Senior Notes [Member] Insurance and Other [Member]	Jun. 30, 2013 Berkshire Hathaway (Parent) [Member] Senior Notes [Member] Insurance and Other [Member]	Jun. 30, 2013 Berkshire Hathaway (Parent) [Member] Senior Notes [Member] Insurance and Other [Member] Minimum [Member]	Jun. 30, 2013 Berkshire Hathaway (Parent) [Member] Senior Notes [Member] Insurance and Other [Member] Maximum [Member]	Feb. 28, 2013 Berkshire Hathaway (Parent) [Member] Senior Notes Due 2013 and 2014 [Member] Insurance and Other [Member]	Jun. 30, 2013 MidAmerican Subsidiaries [Member] Term Debt [Member] Railroad, Utilities and Energy [Member]	Jun. 30, 2013 MidAmerican and Subsidiaries [Member] Railroad, Utilities and Energy [Member]	Mar. 31, 2013 BNSF [Member] Debentures [Member] Railroad, Utilities and Energy [Member]	Jun. 30, 2013 BNSF [Member] Debentures [Member] Railroad, Utilities and Energy [Member]	Mar. 31, 2013 BNSF [Member] Debentures Due 2023 at 3.0% [Member] Railroad, Utilities and Energy [Member]	Jun. 30, 2013 BNSF [Member] Debentures Due 2023 at 3.0% [Member] Railroad, Utilities and Energy [Member]	Mar. 31, 2013 BNSF [Member] Debentures Due 2043 at 4.45% [Member] Railroad, Utilities and Energy [Member]	Jun. 30, 2013 BNSF [Member] Debentures Due 2043 at 4.45% [Member] Railroad, Utilities and Energy [Member]	Jun. 30, 2013 Berkshire Hathaway Subsidiaries [Member] Line of Credit and Commercial Paper Facilities [Member]	May 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes [Member] Finance and Financial Products [Member]	Jan. 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes [Member] Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes [Member] Finance and Financial Products [Member]	Jan. 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2017 at 1.6% [Member] Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2017 at 1.6% [Member] Finance and Financial Products [Member]	Jan. 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2022 at 3.0% [Member] Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2022 at 3.0% [Member] Finance and Financial Products [Member]	May 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2018 and 2043 [Member] Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2018 and 2043 [Member] Finance and Financial Products [Member]	May 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2018 at 1.3% [Member] Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2018 at 1.3% [Member] Finance and Financial Products [Member]	May 31, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2043 at 4.3% [Member] Finance and Financial Products [Member]	Jun. 30, 2013 Berkshire Hathaway Finance Corporation [Member] Senior Notes Due 2043 at 4.3% [Member] Finance and Financial Products [Member]
Debt Instrument [Line Items]
Principal amount of debt issued								$ 2,600,000,000					$ 1,550,000,000		$ 1,500,000,000		$ 700,000,000		$ 800,000,000				$ 500,000,000		$ 275,000,000		$ 225,000,000		$ 1,000,000,000		$ 500,000,000		$ 500,000,000
Issuance date									January 2013							March 2013								January 2013						May 2013
Debt Instrument, Interest Rate, Stated Percentage										0.80%	4.50%							3.00%		4.45%						1.60%		3.00%				1.30%		4.30%
Maturity date, range, start									2016
Maturity date, range, end									2043
Repayment of long-term debt	2,775,000,000	1,915,000,000	311,000,000	524,000,000	1,725,000,000	2,167,000,000						2,600,000,000
Repayment of debt														1,000,000,000								1,000,000,000	500,000,000
Unused lines of credit available																					4,700,000,000
Guarantee obligation							$ 4,300,000,000