Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest income
Loans and leases	$ 1,294,813	$ 1,332,720	$ 1,217,306
Investment securities interest and dividend income	145,200	144,459	160,460
Overnight investments	10,997	6,847	26,245
Total interest income	1,451,010	1,484,026	1,404,011
Interest expense
Deposits	33,240	66,635	76,254
Securities sold under customer repurchase agreements	1,312	1,610	1,995
Federal Home Loan Bank borrowings	8,410	9,763	5,472
Subordinated debt	16,709	16,074	7,099
Other borrowings	1,005	1,775	1,822
Total interest expense	60,676	95,857	92,642
Net interest income	1,390,334	1,388,169	1,311,369
(Benefit) provision for credit losses	(36,835)	58,352	31,441
Net interest income after (benefit) provision for credit losses	1,427,169	1,329,817	1,279,928
Noninterest income
Mortgage income	30,508	39,592	21,126
Marketable equity securities gains, net	34,081	29,395	20,625
Realized gains on investment securities available for sale, net	33,119	60,253	7,115
Other	9,445	7,446	18,431
Total noninterest income	508,002	476,750	415,861
Noninterest expense
Salaries and wages	623,194	590,020	551,112
Employee benefits	135,659	132,244	120,501
Occupancy expense	117,180	117,169	111,179
Equipment expense	119,171	115,535	112,290
Processing fees paid to third parties	59,743	44,791	29,552
FDIC insurance expense	14,132	12,701	10,664
Collection and foreclosure-related expenses	5,442	13,658	11,994
Merger-related expenses	29,463	17,450	17,166
Other	129,526	145,117	139,283
Total noninterest expense	1,233,510	1,188,685	1,103,741
Income before income taxes	701,661	617,882	592,048
Income taxes	154,202	126,159	134,677
Net income	547,459	491,723	457,371
Preferred stock dividends	18,544	14,062	0
Net income available to common shareholders	$ 528,915	$ 477,661	$ 457,371
Average shares outstanding (in shares)	9,816,405	10,056,654	11,141,069
Net income per share	$ 53.88	$ 47.50	$ 41.05
Cash dividends (in dollars per share)	$ 1.88	$ 1.67	$ 1.60
Wealth management services
Noninterest income
Revenue from contracts with customers	$ 128,788	$ 102,776	$ 99,241
Service charges on deposit accounts
Noninterest income
Revenue from contracts with customers	94,756	87,662	105,191
Cardholder services, net
Noninterest income
Revenue from contracts with customers	86,684	74,291	69,078
Other service charges and fees
Noninterest income
Revenue from contracts with customers	35,923	30,911	31,644
Mortgage income
Noninterest income
Revenue from contracts with customers	33,140	24,122	24,304
Insurance commissions
Noninterest income
Revenue from contracts with customers	15,556	14,544	12,810
ATM income
Noninterest income
Revenue from contracts with customers	$ 6,002	$ 5,758	$ 6,296