Loans and Allowance for Credit Losses (Allowance for Credit Losses on Financing Receivables) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Allowance for credit losses:
Beginning balance	$ 9,781	$ 8,726
Charge-offs	(527)	(317)
Recoveries	175	91
Net charge-offs	(352)	(226)
Provision	489	427
Ending balance	9,918	8,927
Commercial and Residential Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Allowance for credit losses:
Beginning balance	2,460	2,787
Charge-offs	(379)	(29)
Recoveries	9	7
Net charge-offs	(370)	(22)
Provision	451	(475)
Ending balance	2,541	2,290
Residential Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	2,284	1,953
Charge-offs	(138)	(223)
Recoveries	13	11
Net charge-offs	(125)	(212)
Provision	200	390
Ending balance	2,359	2,131
Commercial Real Estate Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	2,594	2,610
Recoveries	10	11
Net charge-offs	10	11
Provision	39	291
Ending balance	2,643	2,912
Commercial Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	2,241	1,145
Charge-offs		(65)
Recoveries	143	58
Net charge-offs	143	(7)
Provision	(226)	200
Ending balance	2,158	1,338
Consumer Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	202	231
Charge-offs	(10)
Recoveries		4
Net charge-offs	(10)	4
Provision	25	21
Ending balance	$ 217	$ 256