Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest Income:
Interest and fees on loans and leases	$ 552,441	$ 511,612	$ 489,372
Taxable interest and dividends on securities	190,061	189,408	174,579
Non-taxable interest on securities	15,948	17,064	21,621
Loans held for sale	1,590	857	2,068
Total interest income	760,040	718,941	687,640
Interest Expense:
Deposits	46,031	44,162	46,582
Securities sold under agreements to repurchase and other borrowings	16,861	19,388	20,800
Federal Home Loan Bank advances	22,858	16,909	16,229
Long-term debt	9,665	10,041	7,301
Total interest expense	95,415	90,500	90,912
Net interest income	664,625	628,441	596,728
Provision for loan and lease losses	49,300	37,250	33,500
Net interest income (loss) after provision for loan and lease losses	615,325	591,191	563,228
Non-interest Income:
Deposit service fees	136,578	103,431	98,968
Loan and lease related fees	25,594	23,212	21,860
Wealth and investment services	32,486	34,946	34,771
Mortgage banking activities	7,795	4,070	16,359
Increase in cash surrender value of life insurance policies	13,020	13,178	13,770
Gain on sale of investment securities, net	609	5,499	712
Impairment loss on securities recognized in earnings	(110)	(1,145)	(7,277)
Other income	23,573	18,917	11,887
Total non-interest income	239,545	202,108	191,050
Non-interest Expense:
Compensation and benefits	297,517	270,151	264,835
Occupancy	48,836	47,325	48,794
Technology and equipment	80,026	61,993	60,326
Intangible assets amortization	6,340	2,685	4,919
Marketing	16,053	15,379	15,502
Professional and outside services	11,156	8,296	9,532
Deposit insurance	24,042	22,670	21,114
Other expense	70,584	73,101	72,687
Total non-interest expense	554,554	501,600	497,709
Income before income tax expense	300,316	291,699	256,569
Income tax expense	93,976	91,973	77,113
Net income	206,340	199,726	179,456
Preferred Stock Dividends and Other Adjustments	(9,371)	(11,230)	(11,420)
Earnings applicable to common shareholders	$ 196,969	$ 188,496	$ 168,036
Earnings per common share:
Earnings per common share, Basic (in dollars per share)	$ 2.17	$ 2.10	$ 1.90
Earnings per common share, Diluted (in dollars per share)	$ 2.15	$ 2.08	$ 1.86