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:
Interest and fees on loans	$ 102,656	$ 99,319	$ 98,070
Interest on securities: Taxable	15,359	18,704	21,824
Interest on securities: Nontaxable	2,699	3,001	3,077
Dividends on corporate stock and Federal Home Loan Bank stock	256	253	198
Other interest income	91	69	85
Total interest income	121,061	121,346	123,254
Interest expense:
Deposits	13,590	15,692	20,312
Federal Home Loan Bank advances	14,957	18,158	22,786
Junior subordinated debentures	1,570	1,568	1,989
Other interest expense	248	973	976
Total interest expense	30,365	36,391	46,063
Net interest income	90,696	84,955	77,191
Provision for loan losses	2,700	4,700	6,000
Net interest income after provision for loan losses	87,996	80,255	71,191
Noninterest income:
Trust and investment advisory fees	23,465	22,532	20,670
Mutual fund fees	4,069	4,287	4,423
Financial planning, commissions and other service fees	2,107	1,487	1,299
Wealth management services	29,641	28,306	26,392
Service charges on deposit accounts	3,193	3,455	3,587
Merchant processing fees	10,159	9,905	9,156
Card interchange fees	2,480	2,249	1,975
Income from bank-owned life insurance	2,448	1,939	1,887
Net gains on loan sales and commissions on loans originated for others	14,092	5,074	4,052
Net realized gains on securities	1,223	698	729
Net gains (losses) on interest rate swap contracts	255	6	(36)
Equity in earnings (losses) of unconsolidated subsidiaries	196	(213)	(337)
Other income	1,748	1,536	1,485
Noninterest income, excluding other-than-temporary impairment losses	65,435	52,955	48,890
Total other-than-temporary impairment losses on securities	(28)	(54)	(245)
Portion of loss recognized in other comprehensive income (before tax)	(193)	(137)	(172)
Net impairment losses recognized in earnings	(221)	(191)	(417)
Total noninterest income	65,214	52,764	48,473
Noninterest expense:
Salaries and employee benefits	59,786	51,095	47,429
Net occupancy	6,039	5,295	4,851
Equipment	4,640	4,344	4,099
Merchant processing costs	8,593	8,560	7,822
Outsourced services	3,560	3,530	3,304
FDIC deposit insurance costs	1,730	2,043	3,163
Legal, audit and professional fees	2,240	1,927	1,813
Advertising and promotion	1,730	1,819	1,633
Amortization of intangibles	728	951	1,091
Foreclosed property costs	762	878	841
Debt prepayment penalties	3,908	694	752
Other expenses	8,622	9,237	8,513
Total noninterest expense	102,338	90,373	85,311
Income before income taxes	50,872	42,646	34,353
Income tax expense	15,798	12,922	10,302
Net income	$ 35,074	$ 29,724	$ 24,051
Weighted average common shares outstanding - basic	16,358	16,254	16,114
Weighted average common shares outstanding - diluted	16,401	16,284	16,123
Per share information:
Basic earnings per common share (in dollars per share)	$ 2.13	$ 1.82	$ 1.49
Diluted earnings per common share (in dollars per share)	$ 2.13	$ 1.82	$ 1.49
Cash dividends declared per share (in dollars per share)	$ 0.94	$ 0.88	$ 0.84