Notes payable and other borrowings (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 33,847	$ 34,975
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| U.S. Dollar Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 9,066	9,065
Weighted average interest rate, percentage	3.10%
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Euro Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 7,638	7,806
Weighted average interest rate, percentage	1.10%
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Minimum [Member] \| U.S. Dollar Denominated [Member]
Debt Instrument [Line Items]
Debt maturity year	2019
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Minimum [Member] \| Euro Denominated [Member]
Debt Instrument [Line Items]
Debt maturity year	2020
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Maximum [Member] \| U.S. Dollar Denominated [Member]
Debt Instrument [Line Items]
Debt maturity year	2047
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Maximum [Member] \| Euro Denominated [Member]
Debt Instrument [Line Items]
Debt maturity year	2035
Insurance and Other [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Other borrowings	$ 5,519	5,597
Short-term borrowings	$ 1,696	1,857
Weighted average interest rate, percentage	4.00%
Short-term borrowings, weighted average interest rate	4.40%
Insurance and Other [Member] \| Subsidiaries [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2019
Insurance and Other [Member] \| Subsidiaries [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2045
Insurance and Other [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 9,928	10,650
Weighted average interest rate, percentage	3.80%
Insurance and Other [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2019
Insurance and Other [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2049
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 63,346	62,515
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	4.60%
Senior unsecured debt	$ 8,578	8,577
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2020
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2049
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 29,337	28,196
Weighted average interest rate, percentage	4.50%
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2019
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2064
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Short-term borrowings	$ 2,214	2,516
Short-term borrowings, weighted average interest rate	3.20%
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Burlington Northern Santa Fe and subsidiaries [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 23,217	$ 23,226
Weighted average interest rate, percentage	4.70%
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Burlington Northern Santa Fe and subsidiaries [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2019
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Burlington Northern Santa Fe and subsidiaries [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2097

Year the debt matures, in CCYY format.

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- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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-Publisher FASB
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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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No definition available.

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- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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- Definition

Weighted average interest rate of short-term debt outstanding calculated at point in time.

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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