Fair Value of Financial Instruments (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) security	Dec. 31, 2016 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Acquired Trust Preferred Securities, Number of Securities | security	10
Trust Preferred Securities, Amortized Cost	$ 19,700
Trust Preferred Securities, Fair Value	14,900
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0	$ 0
Collateralized debt obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Impairment losses	$ 3,200	$ 3,200