Notes payable and other borrowings (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 61,147	$ 59,085
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	5.40%
Senior unsecured debt	$ 7,421	7,818
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2018
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2045
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 31,195	29,223
Weighted average interest rate, percentage	4.60%
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Energy Subsidiaries [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2017
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] \| BNSF [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 22,531	22,044
Weighted average interest rate, percentage	4.80%
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| BNSF [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2017
Railroad, Utilities and Energy [Member] \| Subsidiaries [Member] \| BNSF [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2097
Finance and Financial Products [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 13,081	15,384
Finance and Financial Products [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 12,925	14,423
Weighted average interest rate, percentage	2.80%
Finance and Financial Products [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2018
Finance and Financial Products [Member] \| Subsidiaries [Member] \| Berkshire Hathaway Finance Corporation [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2043
Finance and Financial Products [Member] \| Subsidiaries [Member] \| Other Subsidiaries [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 156	961
Weighted average interest rate, percentage	4.50%
Finance and Financial Products [Member] \| Subsidiaries [Member] \| Other Subsidiaries [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2017
Finance and Financial Products [Member] \| Subsidiaries [Member] \| Other Subsidiaries [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2028
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 27,262	27,175
Insurance and Other [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Short-term borrowings	1,819	2,094
Other borrowings	$ 6,797	7,378
Short-term debt, weighted average interest rate	2.90%
Weighted average interest rate, percentage	3.60%
Insurance and Other [Member] \| Subsidiaries [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2017
Insurance and Other [Member] \| Subsidiaries [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2045
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| U.S. Dollar Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 10,614	11,709
Weighted average interest rate, percentage	2.80%
Insurance and Other [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Euro Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 8,032	$ 5,994
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	2017
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

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Name Accounting Standards Codification
-Topic 944
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

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.

+ References

No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Topic 942
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