Loans (Details 6) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Credit risk profile by internally assigned grade
Loans	$ 1,584,594	$ 1,544,845	$ 1,508,425
Pass
Credit risk profile by internally assigned grade
Loans	1,479,820	1,421,862
Special mention
Credit risk profile by internally assigned grade
Loans	44,698	54,990
Substandard
Credit risk profile by internally assigned grade
Loans	31,383	44,694
Substandard non-performing
Credit risk profile by internally assigned grade
Loans	28,693	23,299
Commercial and industrial
Credit risk profile by internally assigned grade
Loans	426,930	393,729	343,956
Commercial and industrial | Pass
Credit risk profile by internally assigned grade
Loans	404,045	356,090
Commercial and industrial | Special mention
Credit risk profile by internally assigned grade
Loans	11,097	15,154
Commercial and industrial | Substandard
Credit risk profile by internally assigned grade
Loans	4,482	17,026
Commercial and industrial | Substandard non-performing
Credit risk profile by internally assigned grade
Loans	7,306	5,459
Construction and development
Credit risk profile by internally assigned grade
Loans	131,253	147,637	159,482
Construction and development | Pass
Credit risk profile by internally assigned grade
Loans	113,559	132,846
Construction and development | Special mention
Credit risk profile by internally assigned grade
Loans	6,831	6,007
Construction and development | Substandard
Credit risk profile by internally assigned grade
Loans		6,368
Construction and development | Substandard non-performing
Credit risk profile by internally assigned grade
Loans	10,863	2,416
Real estate mortgage
Credit risk profile by internally assigned grade
Loans	989,631	966,665	968,440
Real estate mortgage | Pass
Credit risk profile by internally assigned grade
Loans	925,674	896,217
Real estate mortgage | Special mention
Credit risk profile by internally assigned grade
Loans	26,770	33,818
Real estate mortgage | Substandard
Credit risk profile by internally assigned grade
Loans	26,901	21,300
Real estate mortgage | Substandard non-performing
Credit risk profile by internally assigned grade
Loans	10,286	15,330
Consumer
Credit risk profile by internally assigned grade
Loans	36,780	36,814	36,547
Consumer | Pass
Credit risk profile by internally assigned grade
Loans	36,542	36,709
Consumer | Special mention
Credit risk profile by internally assigned grade
Loans		11
Consumer | Substandard non-performing
Credit risk profile by internally assigned grade
Loans	$ 238	$ 94