Investment Securities (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Investments [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Tax Equivalent Interest Adjustment	$ 578,000
Investment Securities average remaining life	4 years 11 months 5 days
Available-for-sale Securities, Gross Realized Losses	$ 2,600,000
Debt securities held-to-maturity, at amortized cost (fair value of $346,199 and $363,779 at March 31, 2018 and December 31, 2017, respectively)	347,622,000		$ 357,197,000
Held-to-maturity Securities, Sold Security, Realized Gain (Loss)	$ 291,000
percent of held to securities sold paid down	96.30%
Other than Temporary Impairment Losses, Investments	$ 0	$ 0
Available-for-sale Securities, Gross Realized Gains	$ 0.000
Asset backed securities mortgage portfolio, term	15 years
Available-for-sale securities	$ 1,079,745,000		1,097,645,000
Available-for-sale Securities Pledged as Collateral	563,000,000		557,000,000
Securities sold at a gain [Member]
Schedule of Investments [Line Items]
Available-for-sale securities	246,961,000
Securities sold at a gain [Member]
Schedule of Investments [Line Items]
Debt securities held-to-maturity, at amortized cost (fair value of $346,199 and $363,779 at March 31, 2018 and December 31, 2017, respectively)	7,366,000
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt securities held-to-maturity, at amortized cost (fair value of $346,199 and $363,779 at March 31, 2018 and December 31, 2017, respectively)	47,767,000		56,785,000
Available-for-sale securities	$ 1,079,745,000		$ 852,645,000