Investment and Mortgage-Backed Securities, Available for Sale (Narrative) (Details)	3 Months Ended
	Mar. 31, 2016 USD ($) security	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	$ 380,672,369		$ 369,140,098
Available-for-sale Securities, Fair Value Disclosure	388,651,412		375,513,870
Available For Sale Securities Pledged as Collateral, Amortized Cost Basis	79,200,000		81,000,000
Available-for-sale Securities Pledged as Collateral, Fair Value	76,800,000		$ 83,200,000
Proceeds From Sale of Available For Sale Securities Including Mortgage Backed Securities	$ 3,200,000	$ 36,400,000
Percent of unrealized losses for securities in a continuous loss position for 12 months or more	32.90%		17.60%
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	17		9
Available-for-sale Securities, Gross Realized Losses	$ 0	47,000
GNMA Mortgage-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	113,500,000		$ 116,800,000
Available-for-sale Securities, Fair Value Disclosure	115,600,000		$ 118,500,000
Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains	$ 258,000	$ 1,500,000