Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest and Dividend Income, Operating [Abstract]
Interest and Fee Income, Loans and Leases	$ 317,208	$ 328,727	$ 321,385
Interest and Dividend Income, Securities, by Classification [Abstract]
Interest Income, Securities, US Treasury and Other US Government	19,458	19,818	26,213
Interest Income, Securities, State and Municipal	8,307	8,436	8,955
Other Interest and Dividend Income	880	739	3,947
Interest and Dividend Income, Operating, Total	345,853	357,720	360,500
Interest Expense, Deposits [Abstract]
Interest Expense, NOW Accounts, Money Market Accounts, and Savings Deposits	1,595	9,142	33,348
Interest Expense, Time Deposits	4,711	12,186	17,494
Interest Expense, Borrowings [Abstract]
Interest Expense, Short-term Borrowings	767	1,110	2,476
Interest Expense, Long-term Debt	8,887	7,652	9,445
Total interest expense	15,960	30,090	62,763
Net interest income	329,893	327,630	297,737
(Recovery of) provision for credit losses	(11,916)	12,054	6,171
Interest Income (Expense), after Provision for Loan Loss, Total	341,809	315,576	291,566
Noninterest Income [Abstract]
Debit card fee income	25,865	22,160	20,250
Bank Owned Life Insurance Income	4,897	4,789	4,557
ATM Fees	2,379	1,773	1,828
Gains (Losses) on Sales of Other Real Estate	(4)	1,207	(222)
Gain (Loss) on Sale of Investments	0	3,286	(421)
Gain on equity securities, net	5,011	2,182	5,118
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	8,152	7,952	4,732
Noninterest Income, Other	10,551	7,386	7,248
Total other income	129,944	125,664	97,193
Noninterest Expense [Abstract]
Salaries	125,585	128,040	119,514
Employee benefits	41,603	37,115	36,806
Occupancy expense	13,039	13,802	12,815
Furniture and equipment expense	10,887	18,805	17,032
Data processing fees	30,539	11,659	10,750
Professional fees and services	27,450	31,303	33,317
Marketing	6,073	5,828	5,753
Insurance	5,917	6,423	3,130
Communication	3,539	4,084	5,351
State tax expense	4,255	3,991	3,829
Amortization of Intangible Assets	1,798	2,263	2,355
Payment for Debt Extinguishment or Debt Prepayment Cost	0	10,529	612
Foundation contribution expense	4,000	3,000	1,500
Miscellaneous	8,833	9,753	11,224
Total other expense	283,518	286,595	263,988
Income before income taxes	188,235	154,645	124,771
Income taxes	34,290	26,722	22,071
Net Income (Loss) Attributable to Parent	$ 153,945	$ 127,923	$ 102,700
Earnings Per Share [Abstract]
Basic (in dollars per share)	$ 9.45	$ 7.85	$ 6.33
Diluted (in dollars per share)	$ 9.37	$ 7.80	$ 6.29
Fiduciary and Trust [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 34,449	$ 28,873	$ 27,768
Deposit Account [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	8,832	8,445	10,835
Bank Servicing [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	29,812	37,611	15,500
Noninterest Income, Other	$ 29,800	$ 37,600	$ 15,500