Note 12 - Net Income Per Common Share - Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net income (loss) attributable to JMP Group LLC	$ 5,069	$ (283)
Basic (in shares)	21,288	21,666
Restricted share units (in shares)	141
Diluted weighted average shares outstanding (in shares)	21,429	21,666
Basic (in dollars per share)	$ 0.24	$ (0.01)
Diluted (in dollars per share)	$ 0.24	$ (0.01)