Note 2 - Mortgage-backed Securities and U.S. Treasury Securities, At Fair Value (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Notional Balance, Interest Only Securities Portfolio, Amount	$ 98,600	$ 111,500
Notional Balance, Inverse Interest Only Securities Portfolio, Amount	26,800	31,500
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	$ 0	$ 36,382

The fair value as of the balance sheet date of firm holdings in debt obligations issued by the US government including short-term Treasury bills, medium-term Treasury notes, and long-term Treasury bonds, as well as debt issued by agencies. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481961/940-320-45-2

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