Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest income
Loans and leases	$ 319,214	$ 336,382	$ 966,525	$ 988,029
Investment securities interest and dividend income	39,246	37,195	105,530	113,293
Overnight investments	3,395	757	6,948	5,828
Total interest income	361,855	374,334	1,079,003	1,107,150
Interest expense
Deposits	8,073	13,468	25,408	55,578
Securities sold under customer repurchase agreements	358	395	1,052	1,236
Federal Home Loan Bank borrowings	2,114	2,156	6,300	7,612
Subordinated debt	4,174	4,351	12,543	11,783
Interest Expense, Other	249	305	768	1,488
Total interest expense	14,968	20,675	46,071	77,697
Net interest income	346,887	353,659	1,032,932	1,029,453
Provision (credit) for loan and lease losses	(1,120)	4,042	(31,697)	52,949
Net interest income after provision for loan and lease losses	348,007	349,617	1,064,629	976,504
Noninterest income
Mortgage income	6,106	13,106	25,026	28,141
Realized gains on investment securities available for sale, net	8,082	21,425	33,119	54,972
Realized gains on investment securities available for sale, net	3,350	(2,701)	31,015	10,461
Other	2,639	2,008	6,363	5,330
Total noninterest income	122,944	120,572	393,743	349,985
Noninterest expense
Salaries and wages	160,947	147,297	462,420	439,185
Employee benefits	32,146	31,788	103,169	100,663
Occupancy expense	29,101	27,990	87,283	85,026
Equipment expense	30,229	29,430	88,934	86,054
Processing fees paid to third parties	15,602	11,927	43,702	32,485
FDIC insurance expense	3,661	2,167	10,261	9,364
Collection and foreclosure-related expenses	836	2,168	3,207	10,171
Merger-related expenses	7,013	3,507	19,601	12,108
Other	33,283	35,388	91,745	108,256
Total noninterest expense	312,818	291,662	910,322	883,312
Income before income taxes	158,133	178,527	548,050	443,177
Income taxes	34,060	35,843	123,873	89,538
Net income	124,073	142,684	424,177	353,639
Preferred stock dividends	4,636	4,636	13,908	9,426
Net income available to common shareholders, basic	119,437	138,048	410,269	344,213
Net income available to common shareholders, diluted	$ 119,437	$ 138,048	$ 410,269	$ 344,213
Weighted average common shares outstanding, basic (in shares)	9,816,405	9,836,629	9,816,405	10,137,321
Weighted average common shares outstanding, diluted (in shares)	9,816,405	9,836,629	9,816,405	10,137,321
Earnings per common share, diluted	$ 12.17	$ 14.03	$ 41.79	$ 33.96
Earnings per common share, basic	$ 12.17	$ 14.03	$ 41.79	$ 33.96
Service charges on deposit accounts
Noninterest income
Revenue from contract with customers	$ 22,879	$ 19,756	$ 65,310	$ 55,503
Cardholder services, net
Noninterest income
Revenue from contract with customers	8,409	6,763	25,858	18,014
Wealth management services
Noninterest income
Revenue from contract with customers	31,935	26,369	95,886	75,152
Service charges on deposit accounts
Noninterest income
Revenue from contract with customers	24,858	20,841	68,277	64,776
ATM income
Noninterest income
Revenue from contract with customers	9,205	7,892	26,653	22,829
Marketable equity securities gains (losses), net
Noninterest income
Revenue from contract with customers	4,000	3,576	11,702	10,453
Gain on extinguishment of debt
Noninterest income
Revenue from contract with customers	$ 1,481	$ 1,537	$ 4,534	$ 4,354