Note 6 - CMBS Structured Pass Through Certificates - Schedule of Activity Related to CMBS I/O Strips (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Unrealized gain (loss)	$ (4,340)	$ 631
Collateralized Mortgage-Backed Securities [Member]
Net interest earned	1,165	611
Unrealized gain (loss)	(4,340)	631
Interest Income and Gains (Loss) on Debt Securities, Trading	$ (3,175)	$ 1,242

Amount of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27357-111563

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration