Loans and Allowance for Credit Losses (Allowance for Credit Losses on Financing Receivables) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for credit losses:
Beginning balance	$ 10,121	$ 9,132	$ 9,781	$ 8,726
Charge-offs	(246)	(287)	(954)	(1,450)
Recoveries	146	105	287	273
Net charge-offs	(100)	(182)	(667)	(1,177)
Provision	307	345	1,214	1,746
Ending balance	10,328	9,295	10,328	9,295
Commercial and Residential Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Allowance for credit losses:
Beginning balance	2,593	2,349	2,460	2,787
Charge-offs			(379)	(54)
Recoveries	3	11	18	27
Net charge-offs	3	11	(361)	(27)
Provision	188	(119)	685	(519)
Ending balance	2,784	2,241	2,784	2,241
Residential Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	2,150	2,096	2,284	1,953
Charge-offs	(109)	(70)	(288)	(393)
Recoveries	5	11	91	32
Net charge-offs	(104)	(59)	(197)	(361)
Provision	95	6	54	451
Ending balance	2,141	2,043	2,141	2,043
Commercial Real Estate Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	2,845	2,802	2,594	2,610
Charge-offs		(100)		(100)
Recoveries	5	8	23	27
Net charge-offs	5	(92)	23	(73)
Provision	87	174	320	347
Ending balance	2,937	2,884	2,937	2,884
Commercial Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	2,210	1,652	2,241	1,145
Charge-offs	(137)	(99)	(263)	(870)
Recoveries	122	67	144	167
Net charge-offs	(15)	(32)	(119)	(703)
Provision	15	184	88	1,362
Ending balance	2,210	1,804	2,210	1,804
Consumer Portfolio Segment [Member]
Allowance for credit losses:
Beginning balance	323	233	202	231
Charge-offs		(18)	(24)	(33)
Recoveries	11	8	11	20
Net charge-offs	11	(10)	(13)	(13)
Provision	(78)	100	67	105
Ending balance	$ 256	$ 323	$ 256	$ 323