Name:	bgcp_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchasesDecreasedBorrowingAmount
Namespace Prefix:	bgcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Line of credit facility capacity available for specific purpose other than for trade purchases increased borrowing amount.

No definition available.

Name:	bgcp_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchasesIncreasedBorrowingAmount
Namespace Prefix:	bgcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Name:	us-gaap_DebtInstrumentMaturityDate
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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer.

No definition available.

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

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.

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

Name:	us-gaap_CreditFacilityAxis=bgcp_CommittedLinesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=bgcp_WarehouseLineDueOctoberTenTwoThousandAndNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=bgcp_WarehouseLineDueSeptemberTwentyFiveTwoThousandNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=bgcp_WarehouseLineDueJuneNineteenTwoThousandNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=bgcp_WarehouseLineDueJuneTwentyTwoThousandEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=bgcp_WarehouseLineDueSeptemberTwentyFiveTwoThousandEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=bgcp_WarehouseLineDueOctoberElevenTwoThousandAndEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: