BUSINESS SEGMENTS (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues - Services and fees									$ 101,929	$ 67,257	$ 59,967
Revenues - Sale of goods									10,596	9,859	16,165
Total revenues	$ 19,761	$ 21,272	$ 45,461	$ 26,031	$ 19,842	$ 20,674	$ 14,947	$ 21,653	112,525	77,116	76,132
Direct cost of services									(29,049)	(23,466)	(24,146)
Cost of goods sold									(3,072)	(14,080)	(11,506)
Selling, general, and administrative expenses									$ (58,322)	(44,453)	$ (36,382)
Restructuring charge						2,548				2,548
Depreciation and Amortization									$ (417)	(505)	$ (611)
Segment income (loss)	(1,326)	3,277	14,669	5,462	(3,864)	(1,253)	(1,056)	(1,258)	22,082	(7,431)	4,098
Corporate and other expenses									(9,975)	(11,621)	(11,638)
Interest income									$ 17	$ 12	26
Loss from equity investment in Great American Real Estate, LLC and Shoon Trading Limited											(21)
Interest expense									$ (834)	$ (1,262)	(2,667)
Income (loss) before income taxes									21,265	(8,681)	1,280
(Provision) benefit for income taxes	(372)	600	5,685	1,775	(1,091)	(387)	(594)	(814)	(7,688)	2,886	(704)
Net income (loss)	(1,046)	2,618	8,569	3,436	(2,902)	(916)	(907)	(1,070)	13,577	(5,795)	576
Net income (loss) attributable to noncontrolling interests									1,772	6	(482)
Net income (loss) attributable to B. Riley Financial, Inc.	(1,004)	$ 1,463	$ 8,664	$ 2,682	(2,822)	$ (868)	$ (777)	$ (1,334)	11,805	(5,801)	1,058
Capital expenditures									239	143	$ 1,160
Total assets	132,420				138,990				132,420	138,990
Capital markets reportable segment [Member]
Segment Reporting Information [Line Items]
Revenues - Services and fees									35,183	19,420
Selling, general, and administrative expenses									(30,229)	(14,185)
Depreciation and Amortization									(519)	(193)
Segment income (loss)									4,435	5,042
Capital expenditures									51	104
Total assets	54,882				48,878				54,882	48,878
Auction and Liquidation Reportable Segment [Member]
Segment Reporting Information [Line Items]
Revenues - Services and fees									35,633	17,166	$ 32,409
Revenues - Sale of goods									10,596	9,859	9,963
Total revenues									46,229	27,025	42,372
Direct cost of services									(15,489)	(10,719)	(11,120)
Cost of goods sold									(3,072)	(14,080)	(7,940)
Selling, general, and administrative expenses									$ (8,170)	(8,481)	$ (11,889)
Restructuring charge										(1,339)
Depreciation and Amortization									$ (191)	(107)	$ (176)
Segment income (loss)									19,307	(7,701)	11,247
Capital expenditures									157	38	423
Total assets	45,892				41,360				45,892	41,360
Valuation and Appraisal Reportable Segment [Member]
Segment Reporting Information [Line Items]
Revenues - Services and fees									31,113	30,671	27,558
Direct cost of services									(13,560)	(12,747)	(13,026)
Selling, general, and administrative expenses									$ (9,101)	(10,721)	$ (8,718)
Restructuring charge										(203)
Depreciation and Amortization									$ (137)	(151)	$ (143)
Segment income (loss)									8,315	6,849	5,671
Capital expenditures									31	1	418
Total assets	12,171				9,527				$ 12,171	$ 9,527
Uk Retail Stores Segment [Member]
Segment Reporting Information [Line Items]
Revenues - Sale of goods											6,202
Cost of goods sold											(3,566)
Selling, general, and administrative expenses											(3,773)
Depreciation and Amortization											(45)
Segment income (loss)											(1,182)
Consolidated Reportable Segment [Member]
Segment Reporting Information [Line Items]
Segment income (loss)									$ 32,057	$ 4,190	$ 15,736
Corporate and Other segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 19,475				$ 39,225				$ 19,475	$ 39,225