SIGNIFICANT ACCOUNTING POLICIES - COVID-19 Impact (narrative) (Details) - USD ($)	2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 26, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
COVID [Line Items]
Proceeds From Sale Of Mortgage Backed Securities MBS Categorized As Trading	$ 170,800,000	$ 171,200,000	$ 176,249,711	$ 43,975,274
Realized Gains On Investments	$ (5,700,000)	$ 5,800,000	(5,744,589)	23,078
Proceeds from Issuance of Long-term Debt			$ 152,165	$ 680,000