Consolidated Statements Of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest income
Interest and fees on loans	$ 301,840	$ 288,213	$ 282,834
Interest on federal funds sold and other short-term investments	1,169	1,255	1,267
Interest and dividends on securities:
Taxable	17,364	23,069	34,564
Tax-exempt	3,524	3,985	4,717
Total interest income	323,897	316,522	323,382
Interest expense
Interest on deposits	32,248	39,075	55,663
Interest on short-term borrowings	303	166	167
Interest on long-term borrowings	13,639	16,553	29,366
Total interest expense	46,190	55,794	85,196
Net interest income	277,707	260,728	238,186
Provision for loan losses	17,862	17,141	13,773
Net interest income after provision for loan losses	259,845	243,587	224,413
Other income
Fees from trust and brokerage services	15,845	13,343	13,637
Fees from deposit services	41,832	42,110	39,220
Bankcard fees and merchant discounts	2,996	2,572	4,786
Other service charges, commissions, and fees	2,229	1,849	1,918
Income from bank-owned life insurance	5,039	5,286	4,673
Income from mortgage banking	2,471	952	662
Other income	2,810	3,563	5,116
Total other-than-temporary impairment losses	(4,955)	(20,958)	(40,756)
Portion of loss recognized in other comprehensive income	(2,421)	544	30,941
Net other-than-temporary impairment losses	(7,376)	(20,414)	(9,815)
Net gains on sales/calls of investment securities	446	1,576	2,006
Net investment securities losses	(6,930)	(18,838)	(7,809)
Total other income	66,292	50,837	62,203
Other expense
Employee compensation	71,402	64,611	60,564
Employee benefits	21,178	17,358	16,749
Net occupancy expense	20,428	18,596	17,246
Other real estate owned (OREO) expense	8,556	7,008	11,131
Equipment expense	8,307	7,976	6,014
Data processing expense	12,532	11,637	10,820
Bankcard processing expense	1,315	1,051	3,284
FDIC insurance expense	6,064	8,468	9,684
Other expense	54,874	47,343	46,720
Total other expense	204,656	184,048	182,212
Income before income taxes	121,481	110,376	104,404
Income taxes	38,874	34,766	32,457
Net income	$ 82,607	$ 75,610	$ 71,947
Earnings per common share:
Basic	$ 1.64	$ 1.62	$ 1.65
Diluted	$ 1.64	$ 1.61	$ 1.65
Dividends per common share	$ 1.24	$ 1.21	$ 1.20
Average outstanding shares:
Basic	50,265,620	46,803,432	43,547,965
Diluted	50,298,019	46,837,363	43,625,183