Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest Income
Interest and Fees on Loans and Leases	$ 333,239	$ 298,522	$ 267,407
Income on Investment Securities
Available-for-Sale	41,892	41,492	42,475
Held-to-Maturity	79,087	89,650	105,860
Deposits	9	8	9
Funds Sold	2,861	1,133	673
Other	812	1,305	1,209
Total Interest Income	457,900	432,110	417,633
Interest Expense
Deposits	12,647	9,626	9,534
Securities Sold Under Agreements to Repurchase	23,406	25,364	25,905
Funds Purchased	12	12	13
Other Debt	4,256	3,021	2,525
Total Interest Expense	40,321	38,023	37,977
Net Interest Income	417,579	394,087	379,656
Provision for Credit Losses	4,750	1,000	(4,864)
Net Interest Income After Provision for Credit Losses	412,829	393,087	384,520
Noninterest Income
Trust and Asset Management	46,203	47,685	47,798
Mortgage Banking	19,895	11,583	7,571
Service Charges on Deposit Accounts	33,654	34,072	35,669
Fees, Exchange, and Other Service Charges	55,176	53,353	53,401
Investment Securities Gains (Losses), Net	10,203	10,160	8,063
Annuity and Insurance	7,017	7,664	8,065
Bank-Owned Life Insurance	6,561	7,039	6,639
Other	18,634	14,663	12,811
Total Noninterest Income	197,343	186,219	180,017
Noninterest Expense
Salaries and Benefits	201,150	191,963	183,028
Net Occupancy	30,252	30,217	37,296
Net Equipment	20,578	20,162	18,479
Data Processing	15,208	16,472	14,979
Professional Fees	10,072	9,660	9,794
FDIC Insurance	8,615	8,669	7,936
Other	64,703	70,961	55,387
Total Noninterest Expense	350,578	348,104	326,899
Income Before Provision for Income Taxes	259,594	231,202	237,638
Provision for Income Taxes	78,133	70,498	74,596
Net Income	$ 181,461	$ 160,704	$ 163,042
Basic Earnings Per Share (in dollars per share)	$ 4.26	$ 3.72	$ 3.71
Diluted Earnings Per Share (in dollars per share)	4.23	3.70	3.69
Dividends Declared Per Share (in dollars per share)	$ 1.89	$ 1.80	$ 1.80
Basic Weighted Average Shares (in shares)	42,644,100	43,217,818	43,899,208
Diluted Weighted Average Shares (in shares)	42,879,783	43,454,877	44,125,456