Year when the debt instrument is scheduled to be fully repaid.

No definition available.

Name:	bgcp_DebtInstrumentMaturityYear
Namespace Prefix:	bgcp_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Final payment due secured loan.

+ References

No definition available.

+ Details

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Namespace Prefix:	bgcp_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Fixed assets pledged for secured loan value.

+ References

No definition available.

+ Details

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Namespace Prefix:	bgcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount prepaid in period related to the company's outstanding debt or loan agreements.

+ References

No definition available.

+ Details

Name:	bgcp_PrepaymentOfLoan
Namespace Prefix:	bgcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

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

- Definition

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

+ References

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=34725769&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=6451184&loc=d3e28551-108399

+ Details

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

- Definition

When presenting a range of interest rates, the highest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentageRateRangeMaximum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

When presenting a range of interest rates, the lowest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentageRateRangeMinimum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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

- Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_GuaranteeObligationsMember
Namespace Prefix:
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Period Type:

Schedule I - Parent Company Only - Commitments, Contingencies and Guarantees - Additional Information (Detail) - USD ($)		12 Months Ended
	Jul. 10, 2015	Dec. 31, 2015	Mar. 13, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Outstanding balance of the secured loan arrangements		$ 23,000,000
8.375% Senior Notes [Member]
Loss Contingencies [Line Items]
Debt instrument gross amount		$ 255,300,000
Stated interest rate		8.375%		8.375%
Senior Notes maturity date		Jul. 19, 2018
Principal amount of notes		$ 240,000,000
Secured Loan Arrangements [Member]
Loss Contingencies [Line Items]
Secured loan arrangements fixed rate, minimum		2.62%
Secured loan arrangements fixed rate, maximum		8.09%
Final payment due, for secured loan arrangement		2016-12
Prepayment of secured loan arrangements				$ 1,500,000
Outstanding balance of the secured loan arrangements		$ 0		0
Debt instrument gross amount			$ 28,200,000
Stated interest rate			3.70%
Senior Notes maturity date		Mar. 13, 2019
Deferred financing costs		$ 200,000
Value of the fixed assets pledged		11,400,000
Parent Company [Member]
Loss Contingencies [Line Items]
Outstanding balance of the secured loan arrangements		$ 23,000,000
Parent Company [Member] \| 8.375% Senior Notes [Member] \| Guarantee Obligations [Member]
Loss Contingencies [Line Items]
Stated interest rate	8.375%
Principal amount of notes	$ 240,000,000
Debt maturity year	2018
Parent Company [Member] \| Secured Loan Arrangements [Member]
Loss Contingencies [Line Items]
Secured loan arrangements fixed rate, minimum		2.62%
Secured loan arrangements fixed rate, maximum		8.09%
Final payment due, for secured loan arrangement		2016-12
Prepayment of secured loan arrangements				1,500,000
Outstanding balance of the secured loan arrangements		$ 0		$ 0
Debt instrument gross amount			$ 28,200,000
Stated interest rate			3.70%
Senior Notes maturity date		Mar. 13, 2019
Deferred financing costs		$ 200,000
Value of the fixed assets pledged		$ 11,400,000