Year the debt matures, in CCYY format.

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The principal amount of new debt issued during the period, excluding premium or discount, if any.

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Amount of short-term and long-term debt and lease obligation.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Weighted average interest rate of debt outstanding.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Notes payable and other borrowings - Narrative (Detail) € in Millions, £ in Millions, $ in Millions, ¥ in Billions	1 Months Ended			3 Months Ended		9 Months Ended
	Apr. 30, 2021 USD ($)	Apr. 30, 2021 JPY (¥)	Jan. 31, 2021 EUR (€)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 EUR (€)	Sep. 30, 2021 EUR (€)	Sep. 30, 2021 JPY (¥)	Sep. 30, 2021 GBP (£)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Notes payable and other borrowings									€ 6,900	¥ 785.5	£ 1,750
Senior Notes [Member] \| Notes Due Ranging From 2026-2041 at 0.5% [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,500	¥ 160.0
Weighted average interest rate, percentage	0.50%	0.50%
Minimum [Member] \| Senior Notes [Member] \| Notes Due Ranging From 2026-2041 at 0.5% [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Debt maturity year	2026	2026
Maximum [Member] \| Senior Notes [Member] \| Notes Due Ranging From 2026-2041 at 0.5% [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Debt maturity year	2041	2041
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings				$ 39,645		$ 39,645						$ 41,522
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Guarantee obligation				$ 3,900		$ 3,900
Insurance and Other [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage				4.10%		4.10%			4.10%	4.10%	4.10%
Insurance and Other [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Gains (loss) attributable to changes in foreign currency exchange rates				$ 264	$ (549)	$ 939	$ (447)
Insurance and Other [Member] \| Senior Notes [Member] \| Notes Due 2041 at 0.5% [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings							$ 1,500	€ 550
Principal amount of debt issued \| €			€ 600
Debt instrument, interest rate, stated percentage			0.50%
Debt maturity year			2041
Insurance and Other [Member] \| Senior Notes [Member] \| Notes Due 2051 at 2.5% [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Repayments of borrowings						750
Principal amount of debt issued						$ 750
Debt instrument, interest rate, stated percentage				2.50%		2.50%			2.50%	2.50%	2.50%
Debt maturity year						2051
Insurance and Other [Member] \| Minimum [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year						2021
Insurance and Other [Member] \| Maximum [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year						2045
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings				$ 75,320		$ 75,320						$ 75,373
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Repayments of borrowings						1,700
Railroad, Utilities and Energy [Member] \| Notes Due Ranging From 2051-2052 at 3.0% [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued						$ 2,100
Weighted average interest rate, percentage				3.00%		3.00%			3.00%	3.00%	3.00%
Railroad, Utilities and Energy [Member] \| Senior Unsecured Debenture [Member] \| Subsidiaries [Member] \| BNSF [Member]
Debt Instrument [Line Items]
Repayments of borrowings						$ 888
Principal amount of debt issued						$ 925
Debt instrument, interest rate, stated percentage				3.30%		3.30%			3.30%	3.30%	3.30%
Debt maturity year						2051
Railroad, Utilities and Energy [Member] \| Minimum [Member] \| Notes Due Ranging From 2051-2052 at 3.0% [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year						2051
Railroad, Utilities and Energy [Member] \| Maximum [Member] \| Notes Due Ranging From 2051-2052 at 3.0% [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year						2052