SELECTED QUARTERLY FINANCIAL DATA (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 19,842	$ 20,674	$ 14,947	$ 21,653	$ 18,188	$ 21,751	$ 15,239	$ 20,954	$ 77,116	$ 76,132	$ 83,936
Operating income (loss)	(3,669)	(1,253)	(1,056)	(1,258)	2,906	782	(1,935)	2,345	(7,431)	4,098	7,441
Income (loss) before income taxes	(3,993)	(1,303)	(1,501)	(1,884)	2,046	103	(2,582)	1,713	(5,801)	1,058	3,521
(Provision) benefit for income taxes	1,091	387	594	814	(1,046)	133	987	(778)	(2,886)	704	1,936
Net income (loss)	(2,902)	(916)	(907)	(1,070)	1,000	236	(1,595)	935	(5,795)	576	4,340
Net (loss) income attributable to B. Riley Financial, Inc.	$ (2,822)	$ (868)	$ (777)	$ (1,334)	$ 934	$ 366	$ (1,531)	$ 1,289	$ (5,801)	$ 1,058	$ 3,521
Earnings (loss) per share:
Basic	$ (0.18)	$ (0.05)	$ (0.16)	$ (0.93)	$ 0.65	$ 0.26	$ (1.07)	$ 0.90	$ (0.60)	$ 0.74	$ 2.46
Diluted	$ (0.18)	$ (0.05)	$ (0.16)	$ (0.93)	$ 0.62	$ 0.24	$ (1.07)	$ 0.87	$ (0.60)	$ 0.71	$ 2.38
Weighted average shares outstanding:
Basic	15,902,607	15,911,482	4,972,203	1,434,107	1,434,107	1,434,107	1,434,107	1,434,107	9,612,154	1,434,107	1,434,107
Diluted	15,902,607	15,911,482	4,972,203	1,434,107	1,495,328	1,494,528	1,434,107	1,482,780	9,612,154	1,494,328	1,480,671