Securities (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Fair value of available for sale and held to maturity securities pledged as collateral	$ 365,100	$ 357,800
Amortized cost of callable debt securities	205,000
Fair value of callable debt securities	$ 197,200
Number of securities in a continuous unrealized loss position total | security	86	71
Available for Sale Securities, Continuous Unrealized Loss Position, Aggregate Losses, Accumulated Investments	$ 25,425	$ 13,535
Individual name issuer trust preferred debt securities
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Number of securities in a continuous unrealized loss position total | security	7	7
Securities in unrealized loss position, number of companies issuing securities | security	5
Amortized cost of trust preferred securities of individual name issuers that are below investment grade	$ 6,100
Unrealized losses of trust preferred securities of individual name issuers that are below investment grade	(417)
Available for Sale Securities, Continuous Unrealized Loss Position, Aggregate Losses, Accumulated Investments	$ 1,016	$ 1,122
Corporate bonds [Member]
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Number of securities in a continuous unrealized loss position total | security	9	6
Available for Sale Securities, Continuous Unrealized Loss Position, Aggregate Losses, Accumulated Investments	$ 888	$ 805
Minimum [Member]
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Maturity period of callable debt securities	2 months
Call features of callable debt securities	1 month
Maximum [Member]
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Maturity period of callable debt securities	19 years
Call features of callable debt securities	3 years