Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow for the extinguishment of long-term borrowing, with the highest claim on the assets of the entity in case of bankruptcy or liquidation, before its maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

Name:	us-gaap_EarlyRepaymentOfSeniorDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30700-110894

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30690-110894

+ Details

Name:	us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

+ References

No definition available.

+ Details

Name:	us-gaap_GainLossOnRepurchaseOfDebtInstrument
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Notes payable and other borrowings - Narrative (Detail) € in Millions, $ in Millions	1 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jan. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Jan. 31, 2017 EUR (€)
Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings			$ 1,145	$ 1,125	$ 1,775
Senior Unsecured Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued \| €								€ 1,100
Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings		$ 1,100
Notes Due 2021 at 0.25% [Member] \| Senior Unsecured Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued \| €								€ 550
Debt instrument, interest rate, stated percentage		0.25%						0.25%
Notes Due 2023 at 0.625% [Member] \| Senior Unsecured Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued \| €								€ 550
Debt instrument, interest rate, stated percentage		0.625%						0.625%
Euro Denominated [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued \| €								€ 6,850
Interest Expense [Member] \| Euro Denominated [Member] \| Senior Notes [Member] \| Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Revaluation attributable to changes in foreign currency exchange rates			990
Berkshire Hathaway Energy Company and Subsidiaries [Member] \| Railroad, Utilities and Energy [Member] \| Debt Due 2022 to 2057 [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,900		$ 1,900
Weighted average interest rate, percentage	3.20%		3.20%
BNSF [Member] \| Railroad, Utilities and Energy [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	4.80%		4.80%
BNSF [Member] \| Railroad, Utilities and Energy [Member] \| Senior Unsecured Debentures [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued							$ 1,250
BNSF [Member] \| Railroad, Utilities and Energy [Member] \| Debentures Due 2027 at 3.25% [Member] \| Senior Unsecured Debentures [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued							$ 500
Debt instrument, interest rate, stated percentage							3.25%
BNSF [Member] \| Railroad, Utilities and Energy [Member] \| Debentures Due 2047 at 4.125% [Member] \| Senior Unsecured Debentures [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued							$ 750
Debt instrument, interest rate, stated percentage							4.125%
Berkshire Hathaway Finance Corporation [Member] \| Finance and Financial Products [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	2.80%		2.80%
Berkshire Hathaway Finance Corporation [Member] \| Finance and Financial Products [Member] \| Senior Notes [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued		$ 1,300
Repayments of borrowings			$ 2,800
Berkshire Hathaway Finance Corporation [Member] \| Finance and Financial Products [Member] \| Notes Due 2019, Floating Rate [Member] \| Senior Notes [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued		950
Berkshire Hathaway Finance Corporation [Member] \| Finance and Financial Products [Member] \| Notes Due 2020, Floating Rate [Member] \| Senior Notes [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued		$ 350
Berkshire Hathaway Energy [Member] \| Railroad, Utilities and Energy [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	5.10%		5.10%
Berkshire Hathaway Energy [Member] \| Railroad, Utilities and Energy [Member] \| Senior Unsecured Debt [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Prepayment of debt	$ 1,000
Berkshire Hathaway Energy [Member] \| Railroad, Utilities and Energy [Member] \| Interest Expense [Member] \| Senior Unsecured Debt [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Pre-tax loss on debt prepayment	$ 410
Subsequent Event [Member] \| Berkshire Hathaway Energy [Member] \| Railroad, Utilities and Energy [Member] \| Debt Due 2021 to 2048 [Member] \| Senior Notes [Member] \| Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued						$ 2,200
Weighted average interest rate, percentage						3.20%