Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest income:
Interest and fees on loans	$ 62,648	$ 71,214	$ 194,295	$ 201,867
Interest on debt securities:
Taxable	5,554	8,004	19,698	21,236
Nontaxable	2,241	969	5,542	2,277
Interest on interest-earning deposits	113	572	500	1,722
Dividends on equity securities	231	319	631	794
Total interest income	70,787	81,078	220,666	227,896
Interest expense:
Interest Expense, Deposits	3,712	13,209	17,983	38,148
Subordinated debentures and notes	2,826	1,956	7,061	5,562
FHLB advances	720	2,203	2,070	5,297
Notes payable and other borrowings	175	664	997	1,785
Total interest expense	7,433	18,032	28,111	50,792
Net interest income	63,354	63,046	192,555	177,104
Provision for credit losses	14,080	1,833	55,935	5,031
Net interest income after provision for credit losses	49,274	61,213	136,620	172,073
Noninterest income:
Total noninterest income	12,629	13,564	35,997	34,758
Noninterest expense:
Employee compensation and benefits	22,040	20,845	66,114	60,884
Occupancy	3,408	3,179	9,940	9,004
Data processing	2,167	2,051	6,393	6,415
Professional fees	755	1,064	2,904	2,847
Merger-related expenses	1,563	393	1,563	17,969
Other	9,591	10,707	29,195	30,012
Total noninterest expense	39,524	38,239	116,109	127,131
Income before income tax expense	22,379	36,538	56,508	79,700
Income tax expense	4,428	7,469	11,055	16,051
Net income	$ 17,951	$ 29,069	$ 45,453	$ 63,649
Earnings per common share
Basic (usd per share)	$ 0.68	$ 1.09	$ 1.73	$ 2.46
Diluted (usd per share)	$ 0.68	$ 1.08	$ 1.73	$ 2.45
Deposit Account [Member]
Noninterest income:
Total noninterest income	$ 2,798	$ 3,246	$ 8,557	$ 9,547
Fiduciary and Trust [Member]
Noninterest income:
Total noninterest income	2,456	2,661	7,283	7,314
Card Services Revenue [Member]
Noninterest income:
Total noninterest income	2,498	2,494	6,970	6,745
Tax credit activity, net [Member]
Noninterest income:
Total noninterest income	748	1,238	2,563	1,968
Financial Service, Other [Member]
Noninterest income:
Total noninterest income	$ 4,129	$ 3,925	$ 10,624	$ 9,184