Investment and Mortgage-Backed Securities, Available for Sale (Schedule of Held to Maturity Securities, Contractual Maturities) (Details)	3 Months Ended
	Mar. 31, 2018 USD ($)
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities, Gross Realized Losses	$ 67,000
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Less Than One Year, Amortized Cost	213,937
One – Five Years, Amortized Cost	12,738,020
Five – Ten Years, Amortized Cost	41,482,362
After Ten Years, Amortized Cost	133,339,409
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis	358,328,622
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Less Than One Year, Fair Value	213,021
One – Five Years, Fair Value	12,739,270
Five – Ten Years, Fair Value	41,522,064
After Ten Years, Fair Value	134,558,974
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	$ 358,852,200