Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest income:
Interest and fees on loans	$ 79,064	$ 64,478	$ 156,037	$ 131,647
Interest on debt securities:
Taxable	4,318	6,587	8,858	14,144
Nontaxable	3,394	1,812	6,473	3,301
Interest on interest-earning deposits	237	87	426	387
Dividends on equity securities	388	227	567	400
Total interest income	87,401	73,191	172,361	149,879
Interest expense:
Interest Expense, Deposits	2,467	4,383	5,130	14,271
Subordinated debentures and notes	2,847	2,316	5,666	4,235
FHLB advances	197	455	392	1,350
Notes payable and other borrowings	152	204	312	822
Total interest expense	5,663	7,358	11,500	20,678
Net interest income	81,738	65,833	160,861	129,201
Provision (benefit) for credit losses	(2,669)	19,591	(2,623)	41,855
Net interest income after provision for credit losses	84,407	46,242	163,484	87,346
Noninterest income:
Total noninterest income	16,204	9,960	27,494	23,368
Noninterest expense:
Employee compensation and benefits	28,132	22,389	57,694	44,074
Occupancy	3,529	3,185	7,280	6,532
Data processing	2,850	2,144	5,740	4,226
Professional fees	1,300	1,287	2,288	2,149
Merger-related expenses	1,949	0	5,091	0
Other	14,696	8,907	27,247	19,604
Total noninterest expense	52,456	37,912	105,340	76,585
Income before income tax expense	48,155	18,290	85,638	34,129
Income tax expense	9,750	3,656	17,307	6,627
Net income	$ 38,405	$ 14,634	$ 68,331	$ 27,502
Earnings per common share
Basic (usd per share)	$ 1.23	$ 0.56	$ 2.19	$ 1.04
Diluted (usd per share)	$ 1.23	$ 0.56	$ 2.18	$ 1.04
Deposit Account [Member]
Noninterest income:
Total noninterest income	$ 3,862	$ 2,616	$ 6,946	$ 5,759
Fiduciary and Trust [Member]
Noninterest income:
Total noninterest income	2,516	2,326	4,999	4,827
Card Services Revenue [Member]
Noninterest income:
Total noninterest income	2,975	2,225	5,471	4,472
Tax credit activity, net [Member]
Noninterest income:
Total noninterest income	1,370	(221)	329	1,815
Financial Service, Other [Member]
Noninterest income:
Total noninterest income	$ 5,481	$ 3,014	$ 9,749	$ 6,495