Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest income:
Loans	$ 348,615	$ 270,238	$ 269,406
Debt securities:
Taxable	18,030	24,629	29,030
Nontaxable	13,814	8,397	3,515
Interest-earning deposits	1,496	620	2,128
Dividends on equity securities	1,275	895	1,055
Total interest income	383,230	304,779	305,134
Interest expense:
Interest Expense, Deposits	10,668	21,049	49,856
Subordinated debentures and notes	10,960	9,885	7,507
FHLB advances	803	2,673	6,668
Other borrowings	605	1,171	2,386
Total interest expense	23,036	34,778	66,417
Net interest income	360,194	270,001	238,717
Provision for credit losses	13,385	65,398	6,372
Net interest income after provision for credit losses	346,809	204,603	232,345
Noninterest income:
Total noninterest income	67,743	54,503	49,176
Noninterest expense:
Employee compensation and benefits	124,904	92,288	81,295
Occupancy	16,286	13,457	12,465
Data processing	12,242	9,050	8,242
Professional fees	4,289	3,940	3,683
Branch-closure expenses	3,441	0	0
Merger-related expenses	22,082	4,174	17,969
Other	62,675	44,250	41,831
Noninterest expense	245,919	167,159	165,485
Income before income tax expense	168,633	91,947	116,036
Income before income tax expense	35,578	17,563	23,297
Income tax expense	$ 133,055	$ 74,384	$ 92,739
Earnings per common share
Basic (usd per share)	$ 3.86	$ 2.76	$ 3.56
Diluted (usd per share)	$ 3.86	$ 2.76	$ 3.55
Deposit Account [Member]
Noninterest income:
Total noninterest income	$ 15,428	$ 11,717	$ 12,801
Fiduciary and Trust [Member]
Noninterest income:
Total noninterest income	10,259	9,732	9,932
Card Services Revenue [Member]
Noninterest income:
Total noninterest income	11,880	9,481	9,154
Tax credit activity, net [Member]
Noninterest income:
Total noninterest income	8,028	6,611	5,393
Total miscellaneous income
Noninterest income:
Total noninterest income	$ 22,148	$ 16,962	$ 11,896