Note 24 - Related Party Transactions - Routine Transactions Recognized in the Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Asset management	$ 396	$ 188	$ 1,021	$ 231
Principal transactions and other income	219	257	974	63
Income (loss) from equity method affiliates	5,490	(1,233)	4,655	(1,340)
Operating expense (income)	129	320	518	628
Interest expense (income)	997	1,931	2,232	3,596
SPAC Fund [Member]
Asset management	292	97	507	50
Principal transactions and other income	(10)	87	468	28
SPAC Series Funds [Member]
Asset management	0	0	319	0
Income (loss) from equity method affiliates	240	0	121	0
U.S. Insurance JV [Member]
Asset management	104	91	195	181
Principal transactions and other income	97	137	259	(30)
Insurance SPAC [Member]
Principal transactions and other income	0	30	0	60
Income (loss) from equity method affiliates	0	(1,334)	0	(1,640)
Insurance SPAC II [Member]
Principal transactions and other income	0	0	40	0
Income (loss) from equity method affiliates	0	0	(107)	0
Insurance SPAC III [Member]
Principal transactions and other income	60	0	120	0
Income (loss) from equity method affiliates	(236)	0	(690)	0
FTAC III Sponsor [Member]
Principal transactions and other income	0	3	0	5
FTAC IV Sponsor [Member]
Principal transactions and other income	30	0	35	0
FTAC V Sponsor [Member]
Principal transactions and other income	5	0	10	0
FTAC Olympus Sponsor [Member]
Principal transactions and other income	28	0	33	0
FTAC Athena Sponsor [Member]
Principal transactions and other income	5		5
FTAC Hera Sponsor [Member]
Principal transactions and other income	2		2
FTAC Parnassus Sponsor [Member]
Principal transactions and other income	2		2
AOI [Member]
Income (loss) from equity method affiliates	64	89	(34)	58
CK Capital Partners B.V. [Member]
Income (loss) from equity method affiliates	(15)	12	(49)	242
SPAC Sponsor Entities [Member]
Income (loss) from equity method affiliates	5,437	0	5,414	0
Duane Morris [Member]
Operating expense (income)	140	331	538	650
FinTech Masala [Member]
Operating expense (income)	(11)	(11)	(20)	(22)
CBF [Member]
Interest expense (income)	0	349	197	877
DGC Trust [Member]
Interest expense (income)	381	482	756	1,015
EBC [Member]
Interest expense (income)	72	72	143	144
Pensco Trust Company, Custodian fbo Edward E. Cohen IRA [Member]
Interest expense (income)	0	0	0	48
JKD Capital Partners I, LTD [Member]
Interest expense (income)	$ 544	$ 1,028	$ 1,136	$ 1,512