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.

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of businesses acquired by the entity during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfBusinessesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3213-108585

+ Details

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Balance Type:	credit
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_ProductOrServiceAxis=brka_AutoDealershipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_ProductOrServiceAxis=brka_InsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=brka_ManufacturerOfAutomotiveFluidMaintenanceProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=brka_AltaLinkMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	dei_LegalEntityAxis=brka_BerkshireHathawayEnergyCompanyMember
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Significant business acquisitions - Narrative (Detail) CAD in Billions, $ in Billions			3 Months Ended
	Dec. 01, 2014 USD ($)	Dec. 01, 2014 CAD	Mar. 31, 2015 USD ($) State Business
Berkshire Hathaway Automotive (formerly Van Tuyl Group) [Member]
Business Acquisition [Line Items]
Aggregate consideration paid for acquisitions \| $			$ 4.1
Berkshire Hathaway Automotive (formerly Van Tuyl Group) [Member] \| Auto Dealerships [Member]
Business Acquisition [Line Items]
Number of businesses			81
Number of states with auto dealerships \| State			10
Berkshire Hathaway Automotive (formerly Van Tuyl Group) [Member] \| Insurance [Member]
Business Acquisition [Line Items]
Number of businesses			2
Berkshire Hathaway Automotive (formerly Van Tuyl Group) [Member] \| Auto Auctions [Member]
Business Acquisition [Line Items]
Number of businesses			2
Berkshire Hathaway Automotive (formerly Van Tuyl Group) [Member] \| Manufacturer of Automotive Fluid Maintenance Products [Member]
Business Acquisition [Line Items]
Number of businesses			1
AltaLink [Member] \| Berkshire Hathaway Energy [Member]
Business Acquisition [Line Items]
Aggregate consideration paid for acquisitions	$ 2.7	CAD 3.1