XML 80 R66.htm IDEA: XBRL DOCUMENT v3.10.0.1

Stock Transactions and Unit Redemptions - Additional Information (Detail) - USD ($)			3 Months Ended				9 Months Ended		12 Months Ended
	Mar. 09, 2018	Apr. 12, 2017	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Aug. 01, 2018	Feb. 07, 2017
Class of Stock [Line Items]
Payment percentage of the gross proceeds from the sale of shares	2.00%	2.00%
Stock repurchase program and unit redemption remaining authorized amount			$ 280,011,172				$ 280,011,172
Redemptions, Number of Units			2,105,457	4,299,936	1,723,654		8,129,047
Class B Common Stock [Member]
Class of Stock [Line Items]
Common stock, issued during the period			0			0	0	0
Common stock outstanding			34,848,107			34,848,107	34,848,107	34,848,107	34,848,000
Common stock, shares issued			34,848,000				34,848,000		34,848,000
Common stock value issued			$ 348,000				$ 348,000		$ 348,000
Class A Common Stock [Member]
Class of Stock [Line Items]
Common stock, issued during the period							25,975,240		1,994,670
Common stock outstanding			293,512,000				293,512,000		256,968,000
Common stock, shares issued			343,690,000				343,690,000		306,218,000
Common stock value issued			$ 3,438,000				$ 3,438,000		$ 3,063,000
Company's repurchase and additional redemption authority amount										$ 300,000,000	$ 300,000,000
Stock repurchase program and unit redemption remaining authorized amount			$ 280,000,000				$ 280,000,000
Class A Common Stock [Member] | April 2017 Sales Agreement
Class of Stock [Line Items]
Maximum number of shares under the controlled equity offering		20,000,000
Class A Common Stock [Member] | Controlled Equity Offerings [Member]
Class of Stock [Line Items]
Common stock, shares issued			20,000,000				20,000,000
Redemptions, Number of Units							8,100,000
Class A Common Stock [Member] | March 2019 Sales Agreement
Class of Stock [Line Items]
Maximum number of shares under the controlled equity offering	300,000,000
Class A Common Stock [Member] | New Controlled Equity Offerings [Member]
Class of Stock [Line Items]
Common stock, shares issued			15,364,556				15,364,556
Common stock value issued			$ 191,600,000				$ 191,600,000

X

- Definition

Maximum number of shares of class A common stock that may be sold under the controlled equity offering sales agreements.

+ References

No definition available.

+ Details

Name:	bgcp_MaximumAmountOfCommonStockOfferAndSale
Namespace Prefix:	bgcp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of units redeemed.

+ References

No definition available.

+ Details

Name:	bgcp_NumberOfUnitsRedeemed
Namespace Prefix:	bgcp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Commission paid to related party broker for sale of shares.

+ References

No definition available.

+ Details

Name:	bgcp_PaymentSpecifiedPercentageOfGrossProceedsFromSaleOfShares
Namespace Prefix:	bgcp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

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

X

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.

+ 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

X

- Definition

Number of new stock issued during the period.

+ 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: 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(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=bgcp_SalesAgreementAprilTwoThousandSeventeenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=bgcp_ControlledEquityOfferingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=bgcp_SalesAgreementMarchTwoThousandEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=bgcp_NewControlledEquityOfferingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: