EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income (loss) attributable to B. Riley Financial, Inc.	$ 3,280	$ (101)	$ 17,301	$ 147
Weighted average shares outstanding:
Basic (in shares)	21,216,829	17,935,254	20,311,231	17,212,716
Effect of dilutive potential common shares:
Restricted stock units and non-vested shares	857,459		628,759	289,705
Contingently issuable shares	44,767		44,767	44,652
Diluted	22,119,055	17,935,254	20,984,757	17,547,073
Basic income (loss) per share (in dollars per share)	$ 0.15	$ (0.01)	$ 0.85	$ 0.01
Diluted income (loss) per share (in dollars per share)	$ 0.15	$ (0.01)	$ 0.82	$ 0.01