Commitments and Off-balance Sheet Items (Summary of Commitments and Contingencies) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Commitment to Sell Loans, Mandatory
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	$ 681	$ 973
Variable Rate	0	0
Commitment to Sell Loans, Non-Mandatory
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	24,628	30,708
Variable Rate	188	677
Standby Letters of Credit
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	959	1,059
Variable Rate	4,736	7,869
Commitments to Fund Loans:
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	47,519	48,439
Variable Rate	569,970	512,471
Consumer Lines | Commitments to Fund Loans:
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	10,997	10,081
Variable Rate	260,934	237,087
Residential Mortgages | Commitments to Fund Loans:
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	17,255	13,760
Variable Rate	655	765
Commercial Operating Lines | Commitments to Fund Loans:
Commitments and Contingent Liabilities [Line Items]
Fixed Rate	19,267	24,598
Variable Rate	$ 308,381	$ 274,619