Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest income
Loans and leases	$ 326,099	$ 303,233	$ 651,647	$ 594,155
Investment securities interest and dividend income	36,605	40,209	76,098	79,821
Overnight investments	553	7,279	5,071	13,669
Total interest income	363,257	350,721	732,816	687,645
Interest expense
Deposits	17,916	19,158	42,110	32,084
Securities sold under customer repurchase agreements	399	515	841	974
Federal Home Loan Bank borrowings	2,472	1,586	5,456	2,871
Subordinated debt	4,677	1,952	7,432	3,624
Interest Expense, Other	399	162	1,183	272
Total interest expense	25,863	23,373	57,022	39,825
Net interest income	337,394	327,348	675,794	647,820
Provision (credit) for loan and lease losses	20,552	5,198	48,907	16,948
Net interest income after provision for loan and lease losses	316,842	322,150	626,887	630,872
Noninterest income
Mortgage income	9,811	5,038	15,035	8,696
Insurance commissions	64,570	3,144	13,162	14,472
Realized gains on investment securities available for sale, net	13,752	5,719	33,547	5,719
Other	2,697	5,034	3,322	8,953
Total noninterest income	165,402	106,875	229,413	210,538
Noninterest expense
Salaries and wages	146,633	136,526	291,888	268,947
Employee benefits	30,364	30,197	68,875	62,732
Occupancy expense	29,556	26,886	57,036	54,647
Equipment expense	28,774	28,489	56,624	55,229
Processing fees paid to third parties	10,186	6,641	20,558	13,730
FDIC insurance expense	3,731	2,757	7,197	5,417
Collection and foreclosure-related expenses	3,949	3,659	8,003	6,681
Merger-related expenses	4,369	4,084	8,601	5,803
Other	34,117	34,158	72,868	67,868
Total noninterest expense	291,679	273,397	591,650	541,054
Income before income taxes	190,565	155,628	264,650	300,356
Income taxes	36,779	36,269	53,695	69,638
Net income	153,786	119,359	210,955	230,718
Less: Preferred stock dividends	4,790	0	4,790	0
Net income available to common shareholders	$ 148,996	$ 119,359	$ 206,165	$ 230,718
Average shares outstanding (in shares)	10,105,520	11,286,520	10,289,320	11,402,112
Net income per share	$ 14.74	$ 10.56	$ 20.04	$ 20.23
Wealth management services
Noninterest income
Revenue from contract with customers	$ 17,587	$ 18,479	$ 35,747	$ 35,112
Cardholder services, net
Noninterest income
Revenue from contract with customers	5,363	6,455	11,251	12,290
Other service charges and fees
Noninterest income
Revenue from contract with customers	17,522	25,790	43,935	50,855
Merchant services, net
Noninterest income
Revenue from contract with customers	22,371	24,573	48,783	49,574
ATM income
Noninterest income
Revenue from contract with customers	7,145	8,164	14,937	15,586
Realized gains on investment securities available for sale, net
Noninterest income
Revenue from contract with customers	3,189	2,854	6,877	6,145
Gain on extinguishment of debt
Noninterest income
Revenue from contract with customers	$ 1,395	$ 1,625	$ 2,817	$ 3,136