Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest income:
Loans and loans held for sale	$ 647,783	$ 682,328	$ 635,872
Investment securities:
Taxable	129,809	128,363	108,824
Tax-exempt	21,925	21,807	21,107
Total investment securities interest	151,734	150,170	129,931
Total interest income	799,517	832,498	765,803
Deposits:
Interest bearing	3,054	2,963	2,543
Savings and money market accounts	22,385	22,101	24,406
Certificates and other time deposits	10,822	10,844	9,649
Federal funds purchased and securities sold under agreements to repurchase	1,126	991	1,240
Wholesale borrowings	4,662	5,210	3,893
Long-term debt	16,173	14,821	13,287
Total interest expense	58,222	56,930	55,018
Net interest income	741,295	775,568	710,785
Provision for loan losses	45,100	52,279	33,684
Net interest income after provision for loan losses	696,195	723,289	677,101
Noninterest income:
Trust department income	42,125	39,949	34,770
Service charges on deposits	66,460	71,457	74,399
Credit card fees	54,643	52,666	50,542
ATM and other service fees	25,588	24,179	19,155
Bank owned life insurance income	15,747	19,177	16,926
Investment services and insurance	15,423	15,145	12,777
Investment securities gains/(losses), net	957	166	(2,803)
Loan sales and servicing income	9,566	16,044	23,069
Other operating income	38,489	42,741	41,508
Total noninterest income	268,998	281,524	270,343
Noninterest expense:
Salaries, wages, pension and employee benefits	348,808	358,970	354,016
Net occupancy expense	55,937	59,436	49,510
Equipment expense	47,926	48,499	41,875
Stationery, supplies and postage	13,424	15,587	14,199
Bankcard, loan processing and other costs	47,081	45,625	71,929
Professional services	19,578	21,813	40,680
Amortization of intangibles	10,392	11,735	8,392
FDIC insurance expense	20,730	20,481	17,707
Other operating expense	74,814	82,773	85,945
Total noninterest expense	638,690	664,919	684,253
Income before income tax expense	326,503	339,894	263,191
Income tax expense	97,019	101,943	79,507
Net income	229,484	237,951	183,684
Less: Net income allocated to participating shareholders	1,836	1,930	1,545
Preferred Stock dividends	5,876	5,876	5,337
Net income attributable to common shareholders	$ 221,772	$ 230,145	$ 176,802
Basic earnings per common share	$ 1.34	$ 1.39	$ 1.18
Diluted earnings per common share	1.33	1.39	1.18
Cash dividend per common share	$ 0.66	$ 0.64	$ 0.64
Weighted average number of common shares outstanding - basic	165,669	165,296	149,607
Weighted average number of common shares outstanding - diluted	166,127	166,054	150,421