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 income:
Interest and fees on loans	$ 231,469	$ 220,687	$ 230,882
Interest and dividends on investment securities:
Taxable	29,900	31,237	36,847
Exempt from federal taxes	4,357	4,728	4,923
Interest on deposits in banks	1,334	992	1,235
Interest on federal funds sold	7	18	13
Total interest income	267,067	257,662	273,900
Interest expense:
Interest on deposits	13,779	15,800	22,306
Interest on securities sold under repurchase agreements	237	294	579
Interest on long-term debt	2,016	1,936	1,981
Interest in preferred stock pending redemption	0	159	131
Interest on subordinated debentures held by subsidiary trusts	2,574	2,506	5,117
Total interest expense	18,606	20,695	30,114
Net interest income	248,461	236,967	243,786
Provision for loan losses	(6,622)	(6,125)	40,750
Net interest income after provision for loan losses	255,083	243,092	203,036
Non-interest income:
Other service charges, commissions and fees	40,742	35,977	34,226
Income from the origination and sale of loans	23,940	34,254	41,790
Wealth management revenues	18,996	17,085	14,314
Service charges on deposit accounts	16,567	16,837	17,412
Investment securities gains, net	61	1	348
Other income	11,095	7,525	6,771
Total non-interest income	111,401	111,679	114,861
Non-interest expense:
Salaries and wages	96,513	94,002	89,833
Employee benefits	30,130	30,338	29,345
Occupancy, net	17,796	16,587	15,786
Furniture and equipment	13,816	12,554	12,859
Outsourced technology services	9,423	9,029	8,826
FDIC insurance premiums	4,608	5,057	6,470
Professional fees	4,882	4,773	4,044
OREO expense, net of income	(272)	2,291	9,400
Mortgage servicing rights amortization	2,361	2,787	3,501
Mortgage servicing rights impairment recovery	(136)	(99)	(771)
Core deposit intangibles amortization	2,251	1,418	1,420
Other expenses	47,480	43,332	45,922
Loss Contingency Expense	4,000	0	3,000
Acquisition Expense	4,017	0	0
Total non-interest expense	236,869	222,069	229,635
Income before income tax expense	129,615	132,702	88,262
Income tax expense	45,214	46,566	30,038
Net income	84,401	86,136	58,224
Preferred stock dividends	0	0	3,300
Net income available to common shareholders	$ 84,401	$ 86,136	$ 54,924
Basic earnings per common share	$ 1.89	$ 1.98	$ 1.28
Diluted earnings per common share	$ 1.87	$ 1.96	$ 1.27