Investment and Mortgage-Backed Securities, Available for Sale (Schedule of Temporarily Impaired Securities, Fair Value and Unrealized losses) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available For Sale, Percent of Unrealized Losses for Securities in a Continuous Loss Position, 12 Months or Longer	25.40%	34.60%
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 149,646,750	$ 100,967,638
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	33,403,293	33,529,120
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	183,050,043	134,496,758
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	2,098,350	811,332
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	714,138	429,858
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	2,812,488	1,241,190
SBA Bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	35,400,695	24,433,422
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5,383,454	5,588,532
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	40,784,149	30,021,954
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	266,288	151,459
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	62,047	38,059
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	328,335	189,518
Tax Exempt Municipal Bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	18,123,386	4,406,162
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	4,216,431	4,328,229
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	22,339,817	8,734,391
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	300,371	13,852
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	145,404	42,999
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	445,775	56,851
Taxable Municipal Bonds [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		1,997,130
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,997,130
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses		19,703
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses		19,703
Mortgage-Backed Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	86,647,947	62,574,910
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	23,803,408	23,612,359
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	110,451,355	86,187,269
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	1,407,637	624,772
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	506,687	348,800
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	$ 1,914,324	$ 973,572