Note 24 - Consolidating Financial Statements - Condensed Consolidating Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues
Investment banking	$ 11,879	$ 20,662
Brokerage	4,535	4,664
Asset management fees	1,703	6,425
Principal transactions	5,288	(3,620)
Loss on sale, payoff and mark-to-market of loans	(17)	(182)
Net dividend income	296	296
Other income (loss)	(35)	49
Equity earnings (losses) of subsidiaries
Non-interest revenues	23,649	28,294
Interest income	14,291	12,710
Interest expense	(10,773)	(9,702)
Net interest income (expense)	3,518	3,008
Total net revenues (losses) after provision for loan losses	27,167	27,211
Gain (loss) on sale, payoff and mark-to-market of loans	(17)	(182)
Loss on repurchase, reissuance or early retirement of debt		(2,626)
Reversal (provision) for loan losses		(1,465)
Non-interest expenses
Compensation and benefits	17,222	24,261
Administration	1,929	2,233
Brokerage, clearing and exchange fees	701	777
Travel and business development	1,021	954
Managed deal expense	533	1,566
Communications and technology	1,053	1,062
Occupancy	1,423	1,117
Professional fees	1,456	1,905
Depreciation	297	264
Other	495	387
Total non-interest expenses	26,130	34,526
Net income (loss) before income tax expense	1,037	(7,315)
Income tax expense (benefit)	(4,102)	(5,568)
Net income	5,139	(1,747)
Net Income (Loss) Attributable to Noncontrolling Interest, Total	70	(1,464)
Net income attributable to JMP Group LLC	5,069	(283)
Reportable Legal Entities [Member] | Parent Company [Member]
Revenues
Investment banking
Brokerage
Asset management fees
Principal transactions	418	(3,176)
Loss on sale, payoff and mark-to-market of loans
Net dividend income	102	271
Other income (loss)	29
Equity earnings (losses) of subsidiaries	10,889	3,519
Non-interest revenues	11,438	614
Interest income	950	664
Interest expense	(1,056)	(1,144)
Net interest income (expense)	(106)	(480)
Total net revenues (losses) after provision for loan losses	11,332	149
Gain (loss) on sale, payoff and mark-to-market of loans
Loss on repurchase, reissuance or early retirement of debt
Reversal (provision) for loan losses		15
Non-interest expenses
Compensation and benefits	581	460
Administration	146	153
Brokerage, clearing and exchange fees
Travel and business development	38	67
Managed deal expense
Communications and technology	1
Occupancy
Professional fees	570	672
Depreciation
Other	278	69
Total non-interest expenses	1,614	1,421
Net income (loss) before income tax expense	9,718	(1,272)
Income tax expense (benefit)	313
Net income	9,405	(1,272)
Net Income (Loss) Attributable to Noncontrolling Interest, Total	167	(1,045)
Net income attributable to JMP Group LLC	9,238	(227)
Reportable Legal Entities [Member] | Subsidiary Issuer [Member]
Revenues
Investment banking
Brokerage
Asset management fees
Principal transactions	62	(18)
Loss on sale, payoff and mark-to-market of loans
Net dividend income	13	3
Other income (loss)
Equity earnings (losses) of subsidiaries	(735)	71
Non-interest revenues	(660)	56
Interest income	1,089	1,141
Interest expense	(2,066)	(2,292)
Net interest income (expense)	(977)	(1,151)
Total net revenues (losses) after provision for loan losses	(1,637)	(1,095)
Gain (loss) on sale, payoff and mark-to-market of loans
Loss on repurchase, reissuance or early retirement of debt
Reversal (provision) for loan losses
Non-interest expenses
Compensation and benefits	1,044	841
Administration	109	137
Brokerage, clearing and exchange fees
Travel and business development	8	15
Managed deal expense
Communications and technology		2
Occupancy
Professional fees	64	84
Depreciation
Other
Total non-interest expenses	1,225	1,079
Net income (loss) before income tax expense	(2,862)	(2,174)
Income tax expense (benefit)	(4,899)	(5,989)
Net income	2,037	3,815
Net Income (Loss) Attributable to Noncontrolling Interest, Total
Net income attributable to JMP Group LLC	2,037	3,815
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Revenues
Investment banking	11,879	20,662
Brokerage	4,535	4,664
Asset management fees	1,742	6,604
Principal transactions	4,808	(426)
Loss on sale, payoff and mark-to-market of loans	(17)	(182)
Net dividend income	181	22
Other income (loss)	(64)	49
Equity earnings (losses) of subsidiaries
Non-interest revenues	23,064	31,393
Interest income	14,428	12,974
Interest expense	(9,827)	(8,335)
Net interest income (expense)	4,601	4,639
Total net revenues (losses) after provision for loan losses	27,665	31,926
Gain (loss) on sale, payoff and mark-to-market of loans	(17)	(182)
Loss on repurchase, reissuance or early retirement of debt		(2,626)
Reversal (provision) for loan losses		(1,480)
Non-interest expenses
Compensation and benefits	15,597	22,960
Administration	1,713	2,122
Brokerage, clearing and exchange fees	701	777
Travel and business development	975	872
Managed deal expense	533	1,566
Communications and technology	1,052	1,060
Occupancy	1,423	1,117
Professional fees	822	1,149
Depreciation	297	264
Other	217	318
Total non-interest expenses	23,330	32,205
Net income (loss) before income tax expense	4,335	(279)
Income tax expense (benefit)	484	421
Net income	3,851	(700)
Net Income (Loss) Attributable to Noncontrolling Interest, Total	(97)	(419)
Net income attributable to JMP Group LLC	3,948	(281)
Consolidation, Eliminations [Member]
Revenues
Investment banking
Brokerage
Asset management fees	(39)	(179)
Principal transactions
Loss on sale, payoff and mark-to-market of loans
Net dividend income
Other income (loss)
Equity earnings (losses) of subsidiaries	(10,154)	(3,590)
Non-interest revenues	(10,193)	(3,769)
Interest income	(2,176)	(2,069)
Interest expense	2,176	2,069
Net interest income (expense)
Total net revenues (losses) after provision for loan losses	(10,193)	(3,769)
Gain (loss) on sale, payoff and mark-to-market of loans
Loss on repurchase, reissuance or early retirement of debt
Reversal (provision) for loan losses
Non-interest expenses
Compensation and benefits
Administration	(39)	(179)
Brokerage, clearing and exchange fees
Travel and business development
Managed deal expense
Communications and technology
Occupancy
Professional fees
Depreciation
Other
Total non-interest expenses	(39)	(179)
Net income (loss) before income tax expense	(10,154)	(3,590)
Income tax expense (benefit)
Net income	(10,154)	(3,590)
Net Income (Loss) Attributable to Noncontrolling Interest, Total
Net income attributable to JMP Group LLC	$ (10,154)	$ (3,590)