Percent of loan balances evaluated collectively for impairment.

No definition available.

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

- Definition

Percent of loan balances evaluated individually for impairment.

+ References

No definition available.

+ Details

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

- Definition

Percent of loan balances that are performing.

+ References

No definition available.

+ Details

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

- Definition

Percent of loan balances that are current as to payment status.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

Amount, after recoveries, of loans and leases that have been written-off.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.11)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_ProvisionForLoanAndLeaseLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the cumulative amount of fees paid by consumer borrowers which have not yet been taken into income and unamortized costs incurred to originate consumer loans and leases, unamortized consumer loan commitments and consumer loan syndication fees, and premiums over or discounts from face amounts of consumer loans that are being amortized into income as an adjustment to yield.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533

+ Details

Name:	us-gaap_UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiumsConsumer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Receivables - Narrative (Detail) (Finance and Financial Products [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Consumer installment loans and finance receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provisions for consumer loan losses	$ 128	$ 161
Loan charge-offs, net of recoveries	151	170
Unamortized acquisition discounts on consumer loans	$ 434		$ 459
Percent of loan balances evaluated collectively for impairment	98.00%
Commercial loans and finance receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of loan balances evaluated individually for impairment	71.00%
Loans and finance receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of loan balances that are performing	98.00%
Percent of loan balances that are current as to payment status	94.00%