Condensed Consolidated Statements of Net Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest income:
Loans, including fees	$ 246,065	$ 280,825	$ 752,209	$ 581,566
Investment securities:
Taxable	20,410	11,118	53,165	33,951
Tax-exempt	2,775	2,136	7,554	5,041
Federal funds sold, securities purchased under agreements to resell and interest-bearing deposits with banks	2,199	1,215	4,538	3,100
Total interest income	271,449	295,294	817,466	623,658
Interest expense:
Deposits	7,267	15,154	28,061	42,215
Federal funds purchased and securities sold under agreements to repurchase	259	509	933	1,515
Corporate and subordinated debentures	3,896	5,034	13,314	8,197
Other borrowings	41	4,249	44	10,813
Total interest expense	11,463	24,946	42,352	62,740
Net interest income	259,986	270,348	775,114	560,918
(Recovery) provision for credit losses	(38,903)	29,797	(156,116)	217,804
Net interest income after (recovery) provision for credit losses	298,889	240,551	931,230	343,114
Noninterest income:
Securities gains, net	64	15	100	15
Other	10,942	8,571	27,062	14,125
Total noninterest income	87,010	114,790	262,315	213,269
Noninterest expense:
Salaries and employee benefits	136,969	134,919	414,709	277,617
Occupancy expense	23,135	23,845	69,310	52,091
Information services expense	18,061	18,855	55,928	40,317
OREO expense and loan related	1,527	1,146	2,769	2,840
Amortization of intangibles	8,543	9,560	26,675	17,232
Supplies, printing and postage expense	2,310	2,755	7,480	5,870
Professional fees	2,415	4,385	7,990	9,727
FDIC assessment and other regulatory charges	4,245	2,849	13,017	7,310
Advertising and marketing	2,185	1,203	5,584	2,548
Extinguishment of debt cost			11,706
Merger and branch consolidation related expense	17,618	21,662	60,598	66,070
Other	15,282	15,708	48,618	37,624
Total noninterest expense	232,290	236,887	724,384	519,246
Earnings:
Income before provision for income taxes	153,609	118,454	469,161	37,137
Provision for income taxes	30,821	23,233	100,464	2,741
Net income	$ 122,788	$ 95,221	$ 368,697	$ 34,396
Earnings per common share:
Basic (in dollars per share)	$ 1.75	$ 1.34	$ 5.22	$ 0.70
Diluted (in dollars per share)	$ 1.74	$ 1.34	$ 5.19	$ 0.69
Weighted average common shares outstanding:
Basic (in shares)	70,066	70,905	70,643	49,330
Diluted (in shares)	70,576	71,076	71,108	49,636
Fees on deposit accounts
Noninterest income:
Noninterest income	$ 26,130	$ 24,346	$ 75,348	$ 59,166
Mortgage banking income
Noninterest income:
Noninterest income	15,560	48,022	52,555	81,040
Trust and investment services income
Noninterest income:
Noninterest income	9,150	7,404	27,461	21,931
Correspondent banking and capital market income
Noninterest income:
Noninterest income	$ 25,164	$ 26,432	$ 79,789	$ 36,992