Investment and Mortgage-Backed Securities, Available for Sale (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013 security	Sep. 30, 2012	Sep. 30, 2013 security	Sep. 30, 2012	Dec. 31, 2012 security
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains			$ 1,274,000	$ 963,000
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	425,477,772		425,477,772		342,936,153
Available-for-sale Securities, Fair Value Disclosure	426,846,798		426,846,798		354,916,216
Available For Sale Securities Pledged as Collateral, Amortized Cost Basis	116,000,000		116,000,000		108,900,000
Available-for-sale Securities Pledged as Collateral, Fair Value	118,300,000		118,300,000		114,400,000
Proceeds From Sale of Available For Sale Securities Including Mortgage Backed Securities	17,100,000	15,600,000	48,900,000	36,900,000
Percent of unrealized losses for securities in a continuous loss position for 12 months or more	2.00%		2.00%		18.80%
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	3		3		2
Available-for-sale Securities, Gross Realized Losses	101,000	0	101,000	0
GNMA Mortgage-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity Securities					47,200,000
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	165,500,000		165,500,000		135,300,000
Available-for-sale Securities, Fair Value Disclosure	169,100,000		169,100,000		141,200,000
Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains	$ 520,000	$ 325,000