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MORTGAGE-BACKED SECURITIES - MBS Portfolio (Details) - USD ($)
Sep. 30, 2021
Dec. 31, 2020
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Fair Value $ 64,390,277 $ 65,178,231
Fixed Rate Mortgages [Member]    
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Fair Value 61,372,000 64,902,000
Interest Only Securities [Member]    
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Fair Value 2,999,000 251,000
Inverse Interest Only [Member]    
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Fair Value $ 19,000 $ 25,000