Short term borrowings excluding repurchase agreements.

No definition available.

Name:	bgcp_ShortTermBorrowingsExcludingRepurchaseAgreements
Namespace Prefix:	bgcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

+ Details

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

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

Name:	us-gaap_LongTermDebtNoncurrent
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the noncurrent portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1336-112600

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1314-112600

+ Details

Name:	us-gaap_LongTermLineOfCredit
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

+ References

+ Details

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

- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

+ Details

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

- Details

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Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=bgcp_SeniorRevolvingCreditAgreementMember
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- Details

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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=bgcp_FourPointThreeSevenFivePercentageSeniorNotesMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_CollateralizedDebtObligationsMember
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Notes Payable, Other and Short-Term Borrowings - Summary Notes Payable, Other and Short-term Borrowings (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jul. 10, 2020	Sep. 27, 2019	Jul. 24, 2018	May 27, 2016
Debt Instrument [Line Items]
Total Notes payable and other borrowings	$ 1,243,248	$ 1,315,935
Short-term borrowings	5,997	3,849
Total Notes payable, other and short-term borrowings	1,249,245	1,319,784
Unsecured Credit Agreement \| Senior Revolving Credit Agreement
Debt Instrument [Line Items]
Unsecured senior revolving credit agreement	188,652	0
5.125% Senior Notes
Debt Instrument [Line Items]
Senior notes	$ 0	255,570
Stated interest rate	5.125%					5.125%
5.375% Senior Notes
Debt Instrument [Line Items]
Senior notes	$ 447,244	446,577
Total Notes payable, other and short-term borrowings					$ 444,200
Stated interest rate	5.375%
3.750% Senior Notes
Debt Instrument [Line Items]
Senior notes	$ 297,317	296,903
Total Notes payable, other and short-term borrowings	$ 297,300			$ 296,100
Stated interest rate	3.75%
4.375% Senior Notes
Debt Instrument [Line Items]
Senior notes	$ 297,252	297,031
Total Notes payable, other and short-term borrowings	$ 297,300		$ 296,800
Stated interest rate	4.375%		4.375%
Collateralized borrowings
Debt Instrument [Line Items]
Collateralized borrowings	$ 12,783	$ 19,854