Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
INTEREST REVENUE:
Loans and leases	$ 404,559	$ 396,441	$ 425,611
Deposits with other banks	532	1,694	1,711
Federal funds sold and securities purchased under agreement to resell			3
Available-for-sale securities:
Taxable	27,755	33,286	39,408
Tax-exempt	14,462	15,547	16,658
Loans held for sale	2,949	2,539	3,033
Total interest revenue	450,257	449,507	486,424
Deposits:
Interest bearing demand	7,851	9,645	16,111
Savings	1,614	1,705	2,697
Other time	20,675	29,729	39,797
Federal funds purchased and securities sold under agreement to repurchase	331	297	274
Long-term debt	2,463	1,803	1,446
Junior subordinated debt	659	7,376	11,502
Other	2	3	6
Total interest expense	33,595	50,558	71,833
Net interest revenue	416,662	398,949	414,591
Provision for credit losses		7,500	28,000
Net interest revenue, after provision for credit losses	416,662	391,449	386,591
NONINTEREST REVENUE:
Mortgage lending	22,671	44,977	56,919
Credit card, debit card and merchant fees	35,303	33,005	31,705
Deposit service charges	50,622	52,905	56,877
Security gains, net	37	46	442
Insurance commissions	114,842	97,700	90,138
Wealth management	23,531	22,966	20,872
Other	22,140	23,467	23,196
Total noninterest revenue	269,146	275,066	280,149
NONINTEREST EXPENSE:
Salaries and employee benefits	307,828	306,696	304,624
Occupancy, net of rental income	41,345	41,109	42,140
Equipment	16,869	18,386	20,849
Deposit insurance assessments	8,190	11,755	16,478
Voluntary early retirement expense		10,850
Write-off and amortization of bond issue cost	48	2,995	153
Other	144,126	143,058	164,949
Total noninterest expense	518,406	534,849	549,193
Income before income taxes	167,402	131,666	117,547
Income tax expense	50,652	37,551	33,252
Net Income	$ 116,750	$ 94,115	$ 84,295
Earnings per share: Basic (in dollars per share)	$ 1.22	$ 0.99	$ 0.90
Earnings per share: Diluted (in dollars per share)	$ 1.21	$ 0.99	$ 0.90