Loans (Narrative) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Deferred Income	$ 12,300,000		$ 12,200,000
Troubled Debt Restructuring, Classification removed	324,000	$ 0
Partial Charge-Offs On Impaired Loans	9,972,000		10,040,000
Impaired Financing Receivable, Related Allowance	1,207,000		684,000
Recorded investment, related to loans	6,100,000		3,500,000
Troubled Debt Restructuring Included In Nonaccrual Loans	24,000,000		38,500,000
TDRs included in accruing loan totals	18,800,000		20,200,000
Nonaccrual Trouble Debt Restructuring Current	18,500,000		32,400,000
Commitments to lend additional funds to borrowers whose terms had been modified in a TDR	800,000		1,300,000
Specific reserves related to troubled debt restructuring	700,000		500,000
Additional Specific Reserves Related To Troubled Debt Restructuring	10,000	280,000
Financing Receivable, Modifications, Recorded Investment, During Period	1,835,000	8,085,000
Loan Modifications on Nonacrrual status	$ 500,000	2,600,000
Loan past due period before entering default status	30 days
Financing Receivable, Modifications, Subsequent Default, Recorded Investment, During Period	$ 1,377,000	1,987,000
Deposit Liabilities Reclassified as Loans Receivable	1,400,000		1,900,000
Financing Receivable With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial Charge-Offs On Impaired Loans	5,800,000		7,900,000
Financing Receivable With A Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial Charge-Offs On Impaired Loans	4,200,000		2,100,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period	249,000	379,000
Commercial Real Estate [Member] | Financing Receivable With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Impaired Financing Receivable, Related Allowance	0		0
Commercial Real Estate [Member] | Financing Receivable With A Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Impaired Financing Receivable, Related Allowance	29,000		$ 2,000
Accruing [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period	429,000	3,585,000
Loans modified during period	72,000	60,000
Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period	1,406,000	4,500,000
Loans modified during period	1,300,000	1,900,000
Nonaccrual [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period	249,000	379,000
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period	6,000,000	1,400,000
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period	$ 0	$ 113,000