Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest Income
Interest and Fees on Loans and Leases	$ 439,012	$ 410,597	$ 370,441
Income on Investment Securities
Available-for-Sale	62,174	50,152	46,772
Held-to-Maturity	81,616	84,310	81,740
Deposits	41	34	15
Funds Sold	3,553	3,723	3,882
Other	1,001	1,357	944
Total Interest Income	587,397	550,173	503,794
Interest Expense
Deposits	68,374	41,143	22,332
Securities Sold Under Agreements to Repurchase	17,522	18,519	19,592
Funds Purchased	840	609	123
Short-Term Borrowings	38	145	64
Other Debt	2,908	3,405	4,445
Total Interest Expense	89,682	63,821	46,556
Net Interest Income	497,715	486,352	457,238
Provision for Credit Losses	16,000	13,425	16,900
Net Interest Income After Provision for Credit Losses	481,715	472,927	440,338
Noninterest Income
Trust and Asset Management	44,233	43,877	45,430
Mortgage Banking	13,686	8,437	12,949
Service Charges on Deposit Accounts	30,074	28,811	32,575
Fees, Exchange, and Other Service Charges	57,893	57,482	54,845
Investment Securities Gains (Losses), Net	(3,986)	(3,938)	10,430
Annuity and Insurance	6,934	5,822	6,858
Bank-Owned Life Insurance	7,015	7,199	6,517
Other	27,489	21,233	15,813
Total Noninterest Income	183,338	168,923	185,417
Noninterest Expense
Salaries and Benefits	216,106	213,208	203,729
Net Occupancy	33,800	34,742	32,536
Net Equipment	29,295	23,852	22,078
Data Processing	18,757	17,846	15,483
Professional Fees	10,071	9,992	11,681
FDIC Insurance	5,192	7,732	8,666
Other	66,006	64,252	63,518
Total Noninterest Expense	379,227	371,624	357,691
Income Before Provision for Income Taxes	285,826	270,226	268,064
Provision for Income Taxes	59,913	50,624	83,392
Net Income	$ 225,913	$ 219,602	$ 184,672
Basic Earnings Per Share (in dollars per share)	$ 5.59	$ 5.26	$ 4.37
Diluted Earnings Per Share (in dollars per share)	5.56	5.23	4.33
Dividends Declared Per Share (in dollars per share)	$ 2.59	$ 2.34	$ 2.04
Basic Weighted Average Shares (in shares)	40,384,328	41,714,770	42,280,931
Diluted Weighted Average Shares (in shares)	40,649,570	41,999,399	42,607,057