CONSOLIDATED STATEMENTS OF EARNINGS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
INTEREST INCOME:
Interest and fees on loans	$ 26,445	$ 24,640
Interest on investment securities:
Taxable	6,375	8,804
Exempt from federal income tax	6,579	6,141
Interest on federal funds sold and interest-bearing deposits in banks	176	212
Total interest income	39,575	39,797
INTEREST EXPENSE:
Interest on deposits	867	1,482
Other	37	58
Total interest expense	904	1,540
Net interest income	38,671	38,257
PROVISION FOR LOAN LOSSES	401	1,296
Net interest income after provision for loan losses	38,270	36,961
NONINTEREST INCOME:
Trust fees	3,793	3,454
Service charges on deposit accounts	3,895	3,882
ATM, interchange and credit card fees	3,729	3,676
Real estate mortgage operations	1,384	1,050
Net gain on available-for-sale securities (includes $222 and $346 for the three months ended March 31, 2013 and 2012, respectively, related to accumulated other comprehensive earnings reclassifications)	222	346
Net gain (loss) on sale of foreclosed assets	(316)	6
Other	1,253	884
Total noninterest income	13,960	13,298
NONINTEREST EXPENSE:
Salaries and employee benefits	15,180	14,229
Net occupancy expense	1,766	1,737
Equipment expense	2,281	2,108
FDIC insurance premiums	572	527
ATM, interchange and credit card expenses	1,340	1,249
Professional and service fees	803	737
Printing, stationery and supplies	472	505
Amortization of intangible assets	10	44
Other	5,047	5,332
Total noninterest expense	27,471	26,468
EARNINGS BEFORE INCOME TAXES	24,759	23,791
INCOME TAX EXPENSE (includes $78 and $121 for the three months ended March 31, 2013 and 2012, respectively, related to income tax expense from reclassification items)	6,182	6,035
NET EARNINGS	$ 18,577	$ 17,756
EARNINGS PER SHARE, BASIC	$ 0.59	$ 0.56
EARNINGS PER SHARE, ASSUMING DILUTION	$ 0.59	$ 0.56
DIVIDENDS PER SHARE	$ 0.25	$ 0.24