Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest income
Loans	$ 79,398	$ 79,049	$ 79,203
Federal funds sold	320	255	138
Mortgage loans held for sale	344	231	339
Securities
Taxable	5,657	5,174	5,274
Tax-exempt	1,182	1,330	1,192
Total interest income	86,901	86,039	86,146
Interest expense
Deposits	7,166	10,105	13,170
Securities sold under agreements to repurchase	180	253	332
Federal funds purchased	31	38	45
Federal Home Loan Bank advances	2,461	1,460	2,266
Subordinated debentures	3,113	3,451	3,454
Total interest expense	12,951	15,307	19,267
Net interest income	73,950	70,732	66,879
Provision for loan losses	11,500	12,600	11,469
Net interest income after provision for loan losses	62,450	58,132	55,410
Non-interest income
Investment management and trust services	14,278	13,841	13,260
Service charges on deposit accounts	8,516	8,348	8,600
Bankcard transaction revenue	3,985	3,722	3,313
Gains on sales of mortgage loans held for sale	4,321	2,122	2,321
Gains on sales of securities available for sale			159
Brokerage commissions and fees	2,593	2,219	2,136
Bank owned life insurance income	1,006	1,019	995
Other	3,758	1,973	2,955
Total non-interest income	38,457	33,244	33,739
Non-interest expenses
Salaries and employee benefits	37,960	33,125	33,485
Net occupancy expense	5,651	5,192	4,934
Data processing expense	5,278	5,014	4,834
Furniture and equipment expense	1,306	1,299	1,272
FDIC insurance	1,494	1,655	2,038
Loss (gain) on other real estate owned	1,410	1,716	(11)
Other	12,373	11,580	10,579
Total non-interest expenses	65,472	59,581	57,131
Income before income taxes	35,435	31,795	32,018
Income tax expense	9,634	8,191	9,065
Net income	$ 25,801	$ 23,604	$ 22,953
Net income per share, basic (in dollars per share)	$ 1.86	$ 1.71	$ 1.68
Net income per share, diluted (in dollars per share)	$ 1.85	$ 1.71	$ 1.67