ACQUISITIONS (Details 2) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Weighted average basic shares outstanding (in shares)	26,059,490	18,977,072	22,180,808	17,805,127
Weighted average diluted shares outstanding (in shares)	27,639,862	19,191,035	23,385,014	18,009,158
United Online Inc [Member]
Revenues	$ 92,461	$ 111,340	$ 320,546	$ 298,118
Net (loss) income attributable to B. Riley Financial, Inc.	$ (42)	$ 2,843	$ 11,780	$ (13,657)
Basic (loss) earnings per share (in dollars per share)	$ (0.00)	$ 0.11	$ 0.41	$ (0.55)
Diluted (loss) earnings per share (in dollars per shares)	$ (0.00)	$ 0.11	$ 0.41	$ (0.55)
Weighted average basic shares outstanding (in shares)	32,366,657	25,783,517	28,487,975	24,611,572
Weighted average diluted shares outstanding (in shares)	32,366,657	25,997,480	28,692,181	24,611,572

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e1505-109256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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