Mortgage Servicing Rights, Net - Schedule of Contractually Specified Servicing Fees and Ancillary Fees Earned (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Transfers And Servicing [Abstract]
Servicing fees	$ 26,092	$ 23,734	$ 51,224	$ 45,784
Escrow interest and placement fees	3,867	2,021	6,834	3,480
Ancillary fees	2,374	1,085	3,201	2,408
Total Servicing fees	$ 32,333	$ 26,840	$ 61,259	$ 51,672

Contractually specified servicing fees, ancillary fees, escrow interest and placement fees earned in exchange for servicing financial assets.

No definition available.

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Escrow interest and placement fees amount.

+ References

No definition available.

+ Details

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Namespace Prefix:	bgcp_
Data Type:	xbrli:monetaryItemType
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- Definition

All amounts that are due to the servicer of a financial asset, excluding contractually specified servicing fees and late fees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746

+ Details

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- Definition

All amounts that, per contract, are due to the servicer in exchange for servicing the financial asset and would no longer be received by a servicer if the beneficial owners of the serviced assets (or their trustees or agents) were to exercise their actual or potential authority under the contract to shift the servicing to another servicer. Depending on the servicing contract, those fees may include some or all of the difference between the interest rate collected on the asset being serviced and the rate to be paid to the beneficial owners of the asset.

+ References

+ Details

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- References

No definition available.

+ Details

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