Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest income
Interest and fees on loans	$ 690,909	$ 586,848	$ 378,209
Interest on taxable securities	33,086	40,138	29,006
Interest on nontaxable securities	623	593	900
Interest on deposits in other banks	1,739	8,139	4,984
Interest on federal funds sold	146	676	227
Total interest income	726,503	636,394	413,326
Interest expense
Interest on deposits	59,067	102,533	49,054
Interest on other borrowings	29,683	28,695	20,880
Total interest expense	88,750	131,228	69,934
Net interest income	637,753	505,166	343,392
Provision for loan losses	125,488	19,758	16,667
Provision for unfunded commitments	19,062	0	0
Provision for other credit losses	830	0	0
Provision for credit losses	145,380	19,758	16,667
Net interest income after provision for credit losses	492,373	485,408	326,725
Noninterest income
Service charges on deposit accounts	44,145	50,792	46,128
Mortgage banking activity	374,077	119,409	53,654
Other service charges, commissions and fees	3,914	3,566	2,971
Net gain (loss) on securities	5	138	(37)
Gain on sale of SBA loans	7,226	6,058	2,728
Other noninterest income	17,133	18,150	12,968
Total noninterest income	446,500	198,113	118,412
Noninterest expense
Salaries and employee benefits	360,278	223,938	149,132
Occupancy and equipment	52,349	40,596	29,131
Advertising and marketing	8,046	7,927	5,571
Amortization of intangible assets	19,612	17,713	9,512
Data processing and communications expenses	46,017	38,513	30,385
Legal and other professional fees	15,972	10,634	6,386
Credit resolution-related expenses	5,106	4,082	4,016
Merger and conversion charges	1,391	73,105	20,499
FDIC insurance	14,078	1,945	3,408
Other noninterest expenses	75,780	53,484	35,607
Total noninterest expense	598,629	471,937	293,647
Income before income tax expense	340,244	211,584	151,490
Income tax expense	78,256	50,143	30,463
Net income	$ 261,988	$ 161,441	$ 121,027
Basic earnings per common share (in dollars per share)	$ 3.78	$ 2.76	$ 2.81
Diluted earnings per common share (in dollars per share)	$ 3.77	$ 2.75	$ 2.80
Weighted average common shares outstanding
Basic (in shares)	69,256	58,462	43,142
Diluted (in shares)	69,426	58,614	43,248