Percentage of ownership to be acquired in a potential business acquisition.

No definition available.

Name:	brka_BusinessAcquisitionOwnershipPercentageToBeAcquired
Namespace Prefix:	brka_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate cash committed to be paid for a potential business acquisition.

+ References

No definition available.

+ Details

Name:	brka_BusinessAcquisitionPotentialCashPayment
Namespace Prefix:	brka_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The recovery percentage of the entity's surety bond claim losses that its joint venture partner is obligated to pay.

+ References

No definition available.

+ Details

Name:	brka_ReimbursementRateFromJointVenturePartnerOfSuretyBondClaimLosses
Namespace Prefix:	brka_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

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)(3))

-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 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13(2))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph a(3)

-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13

-Subparagraph 2

-Article 9

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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

- Details

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

Contingencies and Commitments - Narrative (Detail) In Billions, unless otherwise specified			6 Months Ended
	May 01, 2014 Berkshire Hathaway Energy [Member] AltaLink [Member] USD ($)	May 01, 2014 Berkshire Hathaway Energy [Member] AltaLink [Member] CAD	Jun. 30, 2014 Berkshire Hathaway Insurance Group [Member]	Jun. 30, 2014 Berkshire Hathaway Insurance Group [Member] Surety bonds [Member] USD ($)	Jun. 30, 2014 Berkadia Commercial Mortgage (investee) [Member] USD ($)	Jun. 30, 2014 Leucadia National Corporation (venture partner) [Member] Berkadia Commercial Mortgage (investee) [Member]
Commitments and Contingencies [Line Items]
Voting interest in investee					50.00%	50.00%
Guarantee obligation, maximum amount of exposure				$ 2.5
Reimbursement rate from joint venture partner of Company's surety bond claim losses			50.00%
Commercial paper outstanding					2.47
Ownership percentage to be acquired	100.00%	100.00%
Cash committed to be paid for a potential business acquisition	$ 3.0	3.2