Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest income
Interest and fees on loans	$ 286,033	$ 301,840	$ 288,213
Interest on federal funds sold and other short-term investments	613	1,169	1,255
Interest and dividends on securities:
Taxable	16,646	17,364	23,069
Tax-exempt	2,862	3,524	3,985
Total interest income	306,154	323,897	316,522
Interest expense
Interest on deposits	26,531	32,248	39,075
Interest on short-term borrowings	895	303	166
Interest on long-term borrowings	8,887	13,639	16,553
Total interest expense	36,313	46,190	55,794
Net interest income	269,841	277,707	260,728
Provision for loan losses	19,267	17,862	17,141
Net interest income after provision for loan losses	250,574	259,845	243,587
Other income
Fees from trust and brokerage services	16,447	15,845	13,343
Fees from deposit services	40,245	41,832	42,110
Bankcard fees and merchant discounts	3,591	2,996	2,572
Other service charges, commissions, and fees	2,247	2,229	1,849
Income from bank-owned life insurance	5,788	5,039	5,286
Income from mortgage banking	2,571	2,471	952
Other income	2,748	2,810	3,563
Total other-than-temporary impairment losses	(860)	(4,955)	(20,958)
Portion of loss recognized in other comprehensive income	(6,472)	(2,421)	544
Net other-than-temporary impairment losses	(7,332)	(7,376)	(20,414)
Net gains on sales/calls of investment securities	1,523	446	1,576
Net investment securities losses	(5,809)	(6,930)	(18,838)
Total other income	67,828	66,292	50,837
Other expense
Employee compensation	68,074	71,402	64,611
Employee benefits	22,970	21,178	17,358
Net occupancy expense	19,818	20,428	18,596
Other real estate owned (OREO) expense	6,441	8,556	7,008
Equipment expense	7,748	8,307	7,976
Data processing expense	11,394	12,532	11,637
Bankcard processing expense	1,332	1,315	1,051
FDIC insurance expense	6,188	6,064	8,468
Other expense	49,393	54,874	47,343
Total other expense	193,358	204,656	184,048
Income before income taxes	125,044	121,481	110,376
Income taxes	39,416	38,874	34,766
Net income	$ 85,628	$ 82,607	$ 75,610
Earnings per common share:
Basic	$ 1.70	$ 1.64	$ 1.62
Diluted	$ 1.70	$ 1.64	$ 1.61
Dividends per common share	$ 1.25	$ 1.24	$ 1.21
Average outstanding shares:
Basic	50,353,452	50,265,620	46,803,432
Diluted	50,426,078	50,298,019	46,837,363