Note 15 - Net Income (Loss) Per Common Share - Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net loss attributable to JMP Group LLC	$ (6,549)	$ (2,187)
Basic (in shares)	20,189	21,490
Restricted share units (in shares)
Diluted weighted average shares outstanding (in shares)	20,189	21,490
Basic (in dollars per share)	$ (0.32)	$ (0.10)
Diluted (in dollars per share)	$ (0.32)	$ (0.10)