Loans (Past Due Loans) (Details) - USD ($) $ in Thousands		Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		$ 21,120	$ 24,422
Current		3,178,980	3,209,949
Total loans	[1]	3,200,100	3,234,371
Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		6,422	8,708
Current		1,002,674	1,065,478
Total loans		1,009,096	1,074,186
Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Current		112,177	121,371
Total loans		112,177	121,371
Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		4,009	1,154
Current		573,107	574,955
Total loans		577,116	576,109
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		8,857	12,226
Current		1,134,559	1,082,598
Total loans		1,143,416	1,094,824
Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Current		24,689	27,924
Total loans		24,689	27,924
Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		335	681
Current		263,599	263,519
Total loans		263,934	264,200
Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,471	1,510
Current		33,702	35,762
Total loans		35,173	37,272
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		26	143
Current		34,473	38,342
Total loans		34,499	38,485
30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		8,073	8,154
30-59 | Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	901
30-59 | Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
30-59 | Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,194	409
30-59 | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,524	5,381
30-59 | Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
30-59 | Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		335	655
30-59 | Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		995	776
30-59 | Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		25	32
60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,010	755
60-89 | Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1	0
60-89 | Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
60-89 | Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		321	0
60-89 | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,371	652
60-89 | Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
60-89 | Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	26
60-89 | Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		317	76
60-89 | Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	1
Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		11,037	15,513
Over 90 | Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		6,421	7,807
Over 90 | Commercial Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Over 90 | Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		494	745
Over 90 | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,962	6,193
Over 90 | Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Over 90 | Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Over 90 | Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		159	658
Over 90 | Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		$ 1	$ 110

[1] Includes net unamortized loan origination costs of $3.7 million and $3.0 million, respectively, at June 30, 2017 and December 31, 2016 and net unamortized premiums on purchased loans of $854 thousand and $783 thousand, respectively, at June 30, 2017 and December 31, 2016.