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Notes payable and other borrowings - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Subsidiaries [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	4.00%
Euro Denominated [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	1.10%
Euro Denominated [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Gain (loss) attributable to changes in foreign currency exchange rates	$ 170	$ (217)
Berkshire Hathaway Finance Corporation [Member] \| Subsidiaries [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	3.80%
Berkshire Hathaway Finance Corporation [Member] \| Senior Notes [Member] \| Subsidiaries [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Repayments of borrowings	$ 2,700
Berkshire Hathaway Finance Corporation [Member] \| Notes Due 2049 at 4.25% [Member] \| Senior Notes [Member] \| Subsidiaries [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 2,000
Debt instrument, interest rate, stated percentage	4.25%
Berkshire Hathaway Energy and Subsidiaries [Member] \| Debt Due 2029 To 2050 [Member] \| Subsidiaries [Member] \| Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 3,000
Weighted average interest rate, percentage	3.90%
Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Insurance and Other [Member]
Debt Instrument [Line Items]
Guarantee obligation	$ 1,600