Notes payable and other borrowings - Narrative (Detail) € in Millions, $ in Millions	1 Months Ended				3 Months Ended
	Mar. 31, 2015 USD ($)	Mar. 31, 2015 EUR (€)	Feb. 28, 2015 USD ($)	Jan. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)
Senior Notes [Member]
Debt Instrument [Line Items]
Repayment of debt			$ 1,700
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt issued | €		€ 3,000
Senior Unsecured Notes Due 2023 at 0.75% [Member]
Debt Instrument [Line Items]
Principal amount of debt issued | €		€ 750
Debt instrument, interest rate, stated percentage	0.75%	0.75%
Senior Unsecured Notes Due 2027 at 1.125% [Member]
Debt Instrument [Line Items]
Principal amount of debt issued | €		€ 1,250
Debt instrument, interest rate, stated percentage	1.125%	1.125%
Senior Unsecured Notes Due 2035 at 1.625% [Member]
Debt Instrument [Line Items]
Principal amount of debt issued | €		€ 1,000
Debt instrument, interest rate, stated percentage	1.625%	1.625%
Berkshire Hathaway Finance Corporation [Member] | Senior Notes [Member] | Finance and Financial Products [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 1,000
Repayment of debt				1,000
Berkshire Hathaway Finance Corporation [Member] | Senior Notes Due 2017, Floating Rate [Member] | Finance and Financial Products [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				400
Berkshire Hathaway Finance Corporation [Member] | Senior Notes Due 2018, Floating Rate [Member] | Finance and Financial Products [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 600
Berkshire Hathaway Subsidiaries [Member] | Line of Credit and Commercial Paper Facilities [Member]
Debt Instrument [Line Items]
Unused lines of credit available					$ 8,900
Berkshire Hathaway Energy Company and Subsidiaries [Member] | Line of Credit and Commercial Paper Facilities [Member]
Debt Instrument [Line Items]
Unused lines of credit available					5,300
Berkshire Hathaway (Parent) [Member] | Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Guarantee obligation					3,300
BNSF [Member] | Senior Unsecured Debentures [Member] | Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,500
BNSF [Member] | Debentures Due 2025 at 3.0% [Member] | Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 500
Debt instrument, interest rate, stated percentage	3.00%	3.00%
BNSF [Member] | Debentures Due 2045 at 4.15% [Member] | Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,000
Debt instrument, interest rate, stated percentage	4.15%	4.15%
BNSF [Member] | Secured Amortizing Debt Due 2028 [Member] | Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Principal amount of debt issued					$ 500