Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest income:
Interest and fees on loans	$ 76,973	$ 67,169
Interest on debt securities:
Taxable	4,540	7,557
Nontaxable	3,079	1,489
Interest on interest-earning deposits	189	300
Dividends on equity securities	179	173
Total interest income	84,960	76,688
Interest expense:
Interest Expense, Deposits	2,663	9,888
Subordinated debentures and notes	2,819	1,919
FHLB advances	195	895
Notes payable and other borrowings	160	618
Total interest expense	5,837	13,320
Net interest income	79,123	63,368
Provision for credit losses	46	22,264
Net interest income after provision for credit losses	79,077	41,104
Noninterest income:
Total noninterest income	11,290	13,408
Noninterest expense:
Employee compensation and benefits	29,562	21,685
Occupancy	3,751	3,347
Data processing	2,890	2,082
Professional fees	988	862
Merger-related expenses	3,142	0
Other	12,551	10,697
Total noninterest expense	52,884	38,673
Income before income tax expense	37,483	15,839
Income tax expense	7,557	2,971
Net income	$ 29,926	$ 12,868
Earnings per common share
Basic (usd per share)	$ 0.96	$ 0.49
Diluted (usd per share)	$ 0.96	$ 0.48
Deposit Account [Member]
Noninterest income:
Total noninterest income	$ 3,084	$ 3,143
Fiduciary and Trust [Member]
Noninterest income:
Total noninterest income	2,483	2,501
Card Services Revenue [Member]
Noninterest income:
Total noninterest income	2,496	2,247
Tax credit activity, net [Member]
Noninterest income:
Total noninterest income	(1,041)	2,036
Financial Service, Other [Member]
Noninterest income:
Total noninterest income	$ 4,268	$ 3,481