Consolidated Statements of Income - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Interest income
Loans and leases	$ 325,548,000	$ 290,922,000
Investment securities interest and dividend income	39,493,000	39,605,000
Overnight investments	4,518,000	6,397,000
Total interest income	369,559,000	336,924,000
Interest expense
Deposits	24,194,000	12,926,000
Securities sold under customer repurchase agreements	442,000	459,000
Federal Home Loan Bank borrowings	2,984,000	1,285,000
Subordinated debt	2,755,000	1,672,000
Interest Expense, Other	784,000	110,000
Total interest expense	31,159,000	16,452,000
Net interest income	338,400,000	320,472,000
Provision (credit) for loan and lease losses	28,355,000	11,750,000
Net interest income after provision for loan and lease losses	310,045,000	308,722,000
Noninterest income
Mortgage income	5,224,000	3,658,000
Insurance commissions	(51,408,000)	11,328,000
Realized gains on investment securities available for sale, net	19,795,000	0
Other	625,000	3,919,000
Total noninterest income	64,011,000	103,663,000
Noninterest expense
Salaries and wages	145,255,000	132,421,000
Employee benefits	38,511,000	32,535,000
Occupancy expense	27,480,000	27,761,000
Equipment expense	27,850,000	26,740,000
Processing fees paid to third parties	10,372,000	7,089,000
FDIC insurance expense	3,466,000	2,660,000
Collection and foreclosure-related expenses	4,054,000	3,022,000
Merger-related expenses	4,232,000	1,719,000
Other	38,751,000	33,710,000
Total noninterest expense	299,971,000	267,657,000
Income before income taxes	74,085,000	144,728,000
Income taxes	16,916,000	33,369,000
Net income	57,169,000	111,359,000
Less: Preferred stock dividends	0	0
Net income available to common shareholders	$ 57,169,000	$ 111,359,000
Average shares outstanding (in shares)	10,473,119	11,519,008
Net income per share	$ 5.46	$ 9.67
Wealth management services
Noninterest income
Revenue from contract with customers	$ 18,160,000	$ 16,633,000
Cardholder services, net
Noninterest income
Revenue from contract with customers	5,888,000	5,835,000
Other service charges and fees
Noninterest income
Revenue from contract with customers	26,413,000	25,065,000
Merchant services, net
Noninterest income
Revenue from contract with customers	26,412,000	25,001,000
ATM income
Noninterest income
Revenue from contract with customers	7,792,000	7,422,000
Realized gains on investment securities available for sale, net
Noninterest income
Revenue from contract with customers	3,688,000	3,291,000
Gain on extinguishment of debt
Noninterest income
Revenue from contract with customers	$ 1,422,000	$ 1,511,000