Loans (Past Due Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	$ 6,607		$ 10,423
Loans 60 to 89 Days Past Due	3,040		3,065
Loans Over 90 Days Past Due	18,449		12,785
Total Loans Past Due	28,096		26,273
Current Loans	2,265,907		2,120,886
Total loans	2,294,003	[1]	2,147,159	[1]
Nonaccrual loans, included in past due loans	21,000		17,600
Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	373		1,621
Loans 60 to 89 Days Past Due	408		315
Loans Over 90 Days Past Due	10,300		4,995
Total Loans Past Due	11,081		6,931
Current Loans	699,732		617,882
Total loans	710,813		624,813
Commercial Construction and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	0		0
Loans 60 to 89 Days Past Due	0		0
Loans Over 90 Days Past Due	0		0
Total Loans Past Due	0		0
Current Loans	27,842		10,955
Total loans	27,842		10,955
Commercial Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	260		3,760
Loans 60 to 89 Days Past Due	296		982
Loans Over 90 Days Past Due	3,647		633
Total Loans Past Due	4,203		5,375
Current Loans	509,561		483,485
Total loans	513,764		488,860
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	4,840		3,969
Loans 60 to 89 Days Past Due	1,951		1,505
Loans Over 90 Days Past Due	3,658		6,283
Total Loans Past Due	10,449		11,757
Current Loans	682,349		666,825
Total loans	692,798		678,582
Homeowner Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	0		0
Loans 60 to 89 Days Past Due	0		0
Loans Over 90 Days Past Due	0		0
Total Loans Past Due	0		0
Current Loans	24,883		21,832
Total loans	24,883		21,832
Home Equity Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	753		645
Loans 60 to 89 Days Past Due	207		210
Loans Over 90 Days Past Due	528		525
Total Loans Past Due	1,488		1,380
Current Loans	225,373		222,050
Total loans	226,861		223,430
Home Equity Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	252		362
Loans 60 to 89 Days Past Due	114		46
Loans Over 90 Days Past Due	250		202
Total Loans Past Due	616		610
Current Loans	38,713		42,511
Total loans	39,329		43,121
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30 to 59 Days Past Due	129		66
Loans 60 to 89 Days Past Due	64		7
Loans Over 90 Days Past Due	66		147
Total Loans Past Due	259		220
Current Loans	57,454		55,346
Total loans	$ 57,713		$ 55,566

[1] Includes net unamortized loan origination costs of $39 thousand and $31 thousand, respectively, and net unamortized premiums on purchased loans of $83 thousand and $67 thousand, respectively, at December 31, 2012 and 2011.