Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest income
Loans and leases	$ 336,382	$ 315,012	$ 988,029	$ 909,167
Investment securities interest and dividend income	37,195	40,155	113,293	119,976
Overnight investments	757	7,151	5,828	20,820
Total interest income	374,334	362,318	1,107,150	1,049,963
Interest expense
Deposits	13,468	21,737	55,578	53,821
Securities sold under customer repurchase agreements	395	542	1,236	1,516
Federal Home Loan Bank borrowings	2,156	1,316	7,612	4,187
Subordinated debt	4,351	1,774	11,783	5,398
Interest Expense, Other	305	524	1,488	796
Total interest expense	20,675	25,893	77,697	65,718
Net interest income	353,659	336,425	1,029,453	984,245
Provision (credit) for loan and lease losses	4,042	6,766	52,949	23,714
Net interest income after provision for loan and lease losses	349,617	329,659	976,504	960,531
Noninterest income
Mortgage income	13,106	7,438	28,141	16,134
Insurance commissions	(2,701)	(967)	10,461	13,505
Realized gains on investment securities available for sale, net	21,425	1,136	54,972	6,855
Other	2,008	6,176	5,330	15,129
Total noninterest income	120,572	100,930	349,985	311,468
Noninterest expense
Salaries and wages	147,297	137,841	439,185	406,788
Employee benefits	31,788	28,358	100,663	91,090
Occupancy expense	27,990	28,163	85,026	82,810
Equipment expense	29,430	28,770	86,054	83,999
Processing fees paid to third parties	11,927	7,250	32,485	20,980
FDIC insurance expense	2,167	2,440	9,364	7,857
Collection and foreclosure-related expenses	2,168	3,044	10,171	9,725
Merger-related expenses	3,507	3,892	12,108	9,695
Other	35,388	30,667	108,256	98,535
Total noninterest expense	291,662	270,425	883,312	811,479
Income before income taxes	178,527	160,164	443,177	460,520
Income taxes	35,843	35,385	89,538	105,023
Net income	142,684	124,779	353,639	355,497
Less: Preferred stock dividends	4,636	0	9,426	0
Net income available to common shareholders	$ 138,048	$ 124,779	$ 344,213	$ 355,497
Average shares outstanding (in shares)	9,836,629	11,060,462	10,137,321	11,286,984
Net income per share	$ 14.03	$ 11.27	$ 33.96	$ 31.50
Wealth management services
Noninterest income
Revenue from contract with customers	$ 19,756	$ 15,957	$ 55,503	$ 51,069
Cardholder services, net
Noninterest income
Revenue from contract with customers	6,763	6,034	18,014	18,324
Other service charges and fees
Noninterest income
Revenue from contract with customers	20,841	27,112	64,776	77,967
Merchant services, net
Noninterest income
Revenue from contract with customers	26,369	25,212	75,152	74,786
ATM income
Noninterest income
Revenue from contract with customers	7,892	8,237	22,829	23,823
Realized gains on investment securities available for sale, net
Noninterest income
Revenue from contract with customers	3,576	2,960	10,453	9,105
Gain on extinguishment of debt
Noninterest income
Revenue from contract with customers	$ 1,537	$ 1,635	$ 4,354	$ 4,771