8. Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Segment information
Net interest income	$ 24,299	$ 24,243	$ 72,374	$ 72,149
Provision for loan losses	1,900	3,300	4,150	10,950
Noninterest income	8,707	7,776	24,926	22,792
Noninterest expense	23,594	23,258	71,375	69,839
Provision for income taxes	1,952	1,242	5,833	3,036
Net income (loss)	5,560	4,219	15,942	11,116
Total Assets	2,959,846	2,957,841	2,959,846	2,957,841	2,917,928
Average Assets	2,973,511	2,953,313	2,936,311	2,927,458
Commercial Banking [Member]
Segment information
Net interest income	24,482	24,323	72,863	72,356
Provision for loan losses	1,900	3,300	4,150	10,950
Noninterest income	6,242	5,711	18,687	16,928
Noninterest expense	21,772	21,162	65,980	63,930
Provision for income taxes	1,848	1,309	5,828	3,202
Net income (loss)	5,204	4,263	15,592	11,202
Total Assets	2,925,559	2,915,016	2,925,559	2,915,016
Average Assets	2,945,031	2,922,570	2,908,031	2,897,661
Mortgage Banking [Member]
Segment information
Net interest income	161	183	538	583
Provision for loan losses	0	0	0	0
Noninterest income	2,426	2,035	5,924	5,474
Noninterest expense	1,747	1,909	5,015	5,451
Provision for income taxes	252	93	434	182
Net income (loss)	588	216	1,013	424
Total Assets	26,309	35,167	26,309	35,167
Average Assets	20,368	22,524	20,585	20,653
Wealth Management [Member]
Segment information
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Noninterest income	1,290	1,195	4,006	3,887
Noninterest expense	1,059	1,040	3,364	3,295
Provision for income taxes	69	47	192	178
Net income (loss)	162	108	450	414
Total Assets	636	451	636	451
Average Assets	617	494	525	540
OthersMember
Segment information
Net interest income	(344)	(263)	(1,027)	(790)
Provision for loan losses	0	0	0	0
Noninterest income	27	28	80	79
Noninterest expense	294	340	787	739
Provision for income taxes	(217)	(207)	(621)	(526)
Net income (loss)	(394)	(368)	(1,113)	(924)
Total Assets	466,591	469,579	466,591	469,579
Average Assets	462,947	466,416	458,776	464,177
Intersegment Elimination [Member]
Segment information
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Noninterest income	(1,278)	(1,193)	(3,771)	(3,576)
Noninterest expense	(1,278)	(1,193)	(3,771)	(3,576)
Provision for income taxes	0	0	0	0
Net income (loss)	0	0	0	0
Total Assets	(459,249)	(462,372)	(459,249)	(462,372)
Average Assets	$ (455,452)	$ (458,691)	$ (451,606)	$ (455,573)