Loans (Information on Non-Accrual Loans) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 8,408	$ 7,678	$ 7,499
Loans 90 day past due and accruing			54
Total non-performing loans	8,408	7,678	7,553
Interest income that would have been recorded under original terms, non-accrual loans	123	156
Interest income that would have been recorded under original terms	123	156
Net impact on interest income, non-accrual loans	123	156
Net impact on interest income	123	156
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	2,033	1,845	1,915
Interest income that would have been recorded under original terms, non-accrual loans	25	21
Net impact on interest income, non-accrual loans	25	21
Commercial Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	2,088	1,885	2,259
Interest income that would have been recorded under original terms, non-accrual loans	30	41
Net impact on interest income, non-accrual loans	30	41
Commercial Term [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	3,015	1,986	2,100
Interest income that would have been recorded under original terms, non-accrual loans	44	38
Net impact on interest income, non-accrual loans	44	38
Commercial Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	497	1,248	514
Interest income that would have been recorded under original terms, non-accrual loans	11	45
Net impact on interest income, non-accrual loans	11	45
Consumer: Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	464	460	466
Interest income that would have been recorded under original terms, non-accrual loans	5	6
Net impact on interest income, non-accrual loans	5	6
Consumer: Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	311	254	245
Loans 90 day past due and accruing			$ 54
Interest income that would have been recorded under original terms, non-accrual loans	8	5
Net impact on interest income, non-accrual loans	$ 8	$ 5