Loans and Allowance for Credit Losses (Rollforward of TDRs) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	$ 16,624	$ 18,504
New TDRs		345
Disbursements (payments)	(776)	(1,195)
Charge offs	(459)	(89)
Reclassifications/transfer in/(out)	(74)	(108)
Payoffs	(3,170)	(586)
TDR ending balance	12,145	16,871
TDR, related allowance	621	875
Impaired Nonaccrual Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	3,298	5,504
New TDRs		345
Disbursements (payments)	(86)	(952)
Charge offs	(80)
Reclassifications/transfer in/(out)	80	(1,519)
TDR ending balance	3,212	3,378
TDR, related allowance	376	571
Impaired Nonaccrual Loans [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance		1,603
Disbursements (payments)		(66)
Charge offs	(80)
Reclassifications/transfer in/(out)	80	(1,411)
TDR ending balance		126
TDR, related allowance		23
Impaired Nonaccrual Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	83	83
Reclassifications/transfer in/(out)	(83)
TDR ending balance		83
Impaired Nonaccrual Loans [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	337
New TDRs		345
Disbursements (payments)	(13)	(4)
TDR ending balance	324	341
TDR, related allowance	20
Impaired Nonaccrual Loans [Member] | Construction Loans [Member] | Commercial and Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	2,878	3,818
Disbursements (payments)	(73)	(882)
Reclassifications/transfer in/(out)	83	(108)
TDR ending balance	2,888	2,828
TDR, related allowance	356	548
Impaired Accruing Restructured Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	13,326	13,000
Disbursements (payments)	(690)	(243)
Charge offs	(379)	(89)
Reclassifications/transfer in/(out)	(154)	1,411
Payoffs	(3,170)	(586)
TDR ending balance	8,933	13,493
TDR, related allowance	245	304
Impaired Accruing Restructured Loans [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	4,536	3,875
Disbursements (payments)	(63)	(120)
Charge offs		(89)
Reclassifications/transfer in/(out)	542	1,411
Payoffs	(351)	(452)
TDR ending balance	4,664	4,625
TDR, related allowance	194	228
Impaired Accruing Restructured Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	4,818	4,936
Disbursements (payments)	(402)	(101)
Payoffs	(219)
TDR ending balance	4,197	4,835
TDR, related allowance	32	35
Impaired Accruing Restructured Loans [Member] | Construction Loans [Member] | Commercial and Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	3,972	4,189
Disbursements (payments)	(225)	(22)
Charge offs	(379)
Reclassifications/transfer in/(out)	(696)
Payoffs	(2,600)	(134)
TDR ending balance	72	4,033
TDR, related allowance	$ 19	$ 41