Investment and Mortgage-Backed Securities, Held to Maturity (Schedule of investment and mortgage-backed securities held to maturity) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, gross unrealized gains	$ 841,841
Debt Securities, Held-to-maturity, Amortized Cost, before Other-than-temporary Impairment	17,285,858
Held to maturity, gross unrealized losses	169,008
Debt Securities, Held-to-maturity, Fair Value	17,958,691	$ 19,205,287
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	17,285,858
Held to maturity, gross unrealized gains	841,841
Held to maturity, gross unrealized losses	169,008
Debt Securities, Held-to-maturity, Fair Value	$ 17,958,691