Investment and Mortgage-Backed Securities, Held to Maturity (Schedule of investment and mortgage-backed securities held to maturity) (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, gross unrealized gains		$ 81,314
Debt Securities, Held-to-maturity, Amortized Cost, before Other-than-temporary Impairment	$ 23,335,262	23,335,262
Held to maturity, gross unrealized losses		522,056
Debt Securities, Held-to-maturity, Fair Value	22,894,520	22,894,520	$ 27,054,934
Available-for-sale Securities, Gross Realized Losses	67,000
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	998,320	998,320
Held to maturity, gross unrealized gains		0
Held to maturity, gross unrealized losses		27,282
Debt Securities, Held-to-maturity, Fair Value	971,038	971,038
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	22,336,942	22,336,942
Held to maturity, gross unrealized gains		81,314
Held to maturity, gross unrealized losses		494,774
Debt Securities, Held-to-maturity, Fair Value	$ 21,923,482	$ 21,923,482