Represent business combination of right per share.

No definition available.

Name:	rily_BusinessCombinationRightShares
Namespace Prefix:	rily_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of Consideration paid in Warrants.

+ References

No definition available.

+ Details

Name:	rily_BusinessCombinationWarrantConsideration
Namespace Prefix:	rily_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Exercise price per share.

+ References

No definition available.

+ Details

Name:	rily_ClassOfWarrantOrRightsExercisePriceOfWarrantsOrRights1
Namespace Prefix:	rily_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	rily_WarrantsIssued
Namespace Prefix:	rily_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the fair value of the noncontrolling interest in the acquiree at the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472

+ Details

Name:	us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Face amount or stated value per share of common stock.

+ 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_CommonStockParOrStatedValuePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_StatementEquityComponentsAxis=rily_BrBrandWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=rily_MagicJackVocalTecLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=rily_MergerAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=rily_BRBrandAcquisitionLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Acquisitions (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Nov. 14, 2018	Dec. 31, 2019	Oct. 11, 2019	Dec. 31, 2018
Goodwill		$ 223,697		$ 223,368
Warrants issued		200,000
Common stock, par value		$ 0.0001		$ 0.0001
BR Brands Warrants [Member]
Warrants issued		200,000
MagicJack VocalTec [Member] \| Merger Agreement [Member]
Business combination right shares	$ 8.71
Total consideration	$ 143,115
Goodwill	$ 109,674
BR Brand Acquisition LLC [Member]
Total consideration			$ 118,060
Warrant consideration			$ 990
Exercise price (in dollars per share)			$ 26.24
Non-controlling interest			$ 29,373
Transaction costs			$ 570