Notes payable and other borrowings (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Insurance and Other [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 14,556	$ 11,894
Insurance and Other [Member] \| Berkshire Hathaway (Parent) [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 9,903	8,354
Weighted average interest rate, percentage	2.20%
Insurance and Other [Member] \| Berkshire Hathaway (Parent) [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2015
Insurance and Other [Member] \| Berkshire Hathaway (Parent) [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2047
Insurance and Other [Member] \| Insurance and Other Subsidiaries [Member]
Notes payable and other borrowings [Line Items]
Short-term borrowings	$ 1,909	839
Other borrowings	$ 2,744	2,701
Short-term debt, weighted average interest rate	1.80%
Weighted average interest rate, percentage	6.00%
Insurance and Other [Member] \| Insurance and Other Subsidiaries [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2015
Insurance and Other [Member] \| Insurance and Other Subsidiaries [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2044
Railroad, Utilities and Energy [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 57,872	55,579
Railroad, Utilities and Energy [Member] \| Berkshire Hathaway Energy [Member]
Notes payable and other borrowings [Line Items]
Weighted average interest rate, percentage	5.10%
Senior unsecured debt	$ 7,860	7,860
Railroad, Utilities and Energy [Member] \| Berkshire Hathaway Energy [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2017
Railroad, Utilities and Energy [Member] \| Berkshire Hathaway Energy [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2045
Railroad, Utilities and Energy [Member] \| Berkshire Hathaway Energy Subsidiaries [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 28,130	28,439
Weighted average interest rate, percentage	4.90%
Railroad, Utilities and Energy [Member] \| Berkshire Hathaway Energy Subsidiaries [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2015
Railroad, Utilities and Energy [Member] \| Berkshire Hathaway Energy Subsidiaries [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2064
Railroad, Utilities and Energy [Member] \| BNSF [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 21,882	19,280
Weighted average interest rate, percentage	4.90%
Railroad, Utilities and Energy [Member] \| BNSF [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2015
Railroad, Utilities and Energy [Member] \| BNSF [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2097
Finance and Financial Products [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 12,483	12,736
Finance and Financial Products [Member] \| Berkshire Hathaway Finance Corporation [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 11,178	11,178
Weighted average interest rate, percentage	2.70%
Finance and Financial Products [Member] \| Berkshire Hathaway Finance Corporation [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2015
Finance and Financial Products [Member] \| Berkshire Hathaway Finance Corporation [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2043
Finance and Financial Products [Member] \| Other Finance Subsidiaries [Member]
Notes payable and other borrowings [Line Items]
Notes payable and other borrowings	$ 1,305	$ 1,558
Weighted average interest rate, percentage	5.30%
Finance and Financial Products [Member] \| Other Finance Subsidiaries [Member] \| Minimum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2015
Finance and Financial Products [Member] \| Other Finance Subsidiaries [Member] \| Maximum [Member]
Notes payable and other borrowings [Line Items]
Debt maturity year	2036

Year the debt matures, in CCYY format.

No definition available.

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- Definition

Notes payable and other borrowings [Line Items]

+ References

No definition available.

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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

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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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

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 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section H

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- Definition

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 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: 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

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

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13

-Subparagraph 2, 3

-Article 9

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- Definition

Weighted average interest rate of short-term debt outstanding.

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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 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Article 5

-Subsection 19, 20, 22

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