Loans (Past Due Loans) (Details) - USD ($)		Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		$ 20,075,000	$ 24,422,000
Current loans		3,353,996,000	3,209,949,000
Total loans	[1]	3,374,071,000	3,234,371,000
Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		4,960,000	8,708,000
Current loans		1,067,527,000	1,065,478,000
Total loans		1,072,487,000	1,074,186,000
Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
Current loans		138,008,000	121,371,000
Total loans		138,008,000	121,371,000
Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		4,076,000	1,154,000
Current loans		608,258,000	574,955,000
Total loans		612,334,000	576,109,000
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		7,855,000	12,226,000
Current loans		1,198,603,000	1,082,598,000
Total loans		1,206,458,000	1,094,824,000
Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
Current loans		20,790,000	27,924,000
Total loans		20,790,000	27,924,000
Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		1,340,000	681,000
Current loans		256,774,000	263,519,000
Total loans		258,114,000	264,200,000
Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		1,801,000	1,510,000
Current loans		32,552,000	35,762,000
Total loans		34,353,000	37,272,000
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		43,000	143,000
Current loans		31,484,000	38,342,000
Total loans		31,527,000	38,485,000
30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		8,304,000	8,154,000
30-59 | Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		6,000	901,000
30-59 | Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
30-59 | Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		3,793,000	409,000
30-59 | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		1,678,000	5,381,000
30-59 | Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
30-59 | Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		1,340,000	655,000
30-59 | Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		1,458,000	776,000
30-59 | Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		29,000	32,000
60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		2,351,000	755,000
60-89 | Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
60-89 | Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
60-89 | Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		2,000	0
60-89 | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		2,274,000	652,000
60-89 | Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
60-89 | Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	26,000
60-89 | Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		75,000	76,000
60-89 | Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	1,000
Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		9,420,000	15,513,000
Over 90 | Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		4,954,000	7,807,000
Over 90 | Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
Over 90 | Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		281,000	745,000
Over 90 | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		3,903,000	6,193,000
Over 90 | Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
Over 90 | Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		0	0
Over 90 | Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		268,000	658,000
Over 90 | Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans		$ 14,000	$ 110,000

[1] Includes net unamortized loan origination costs of $3.8 million and $3.0 million, respectively, and net unamortized premiums on purchased loans of $878 thousand and $783 thousand, respectively, at December 31, 2017 and 2016.