Loans and Allowance for Credit Losses (Rollforward of TDRs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	$ 16,624	$ 18,504
Disbursements (payments)	(81)	(341)
Charge offs	(379)	(89)
Payoffs	(3,006)
TDR ending balance	13,158	18,074
TDR, related allowance	757	1,049
Impaired Nonaccrual Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	3,298	5,504
Disbursements (payments)	(20)	(212)
Reclassifications/transfer in/(out)	154
TDR ending balance	3,432	5,292
TDR, related allowance	457	800
Impaired Nonaccrual Loans [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance		1,603
Disbursements (payments)		(22)
Reclassifications/transfer in/(out)	154
TDR ending balance	154	1,581
TDR, related allowance		134
Impaired Nonaccrual Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	83	83
TDR ending balance	83	83
Impaired Nonaccrual Loans [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	337
Disbursements (payments)	(4)
TDR ending balance	333
TDR, related allowance	29
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)	(16)	(190)
TDR ending balance	2,862	3,628
TDR, related allowance	428	666
Impaired Accruing Restructured Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
TDR beginning balance	13,326	13,000
Disbursements (payments)	(61)	(129)
Charge offs	(379)	(89)
Reclassifications/transfer in/(out)	(154)
Payoffs	(3,006)
TDR ending balance	9,726	12,782
TDR, related allowance	300	249
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)	(25)	(82)
Charge offs		(89)
Reclassifications/transfer in/(out)	(154)
Payoffs	(187)
TDR ending balance	4,170	3,704
TDR, related allowance	223	148
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)	(33)	(37)
Payoffs	(219)
TDR ending balance	4,566	4,899
TDR, related allowance	36	84
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)	(3)	(10)
Charge offs	(379)
Payoffs	(2,600)
TDR ending balance	990	4,179
TDR, related allowance	$ 41	$ 17