Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income
Interest and fees on loans	$ 586,848	$ 378,209	$ 270,887
Interest on taxable securities	40,138	29,006	20,154
Interest on nontaxable securities	593	900	1,581
Interest on deposits in other banks	8,139	4,984	1,725
Interest on federal funds sold	676	227	0
Total interest income	636,394	413,326	294,347
Interest expense
Interest on deposits	102,533	49,054	19,877
Interest on other borrowings	28,695	20,880	14,345
Total interest expense	131,228	69,934	34,222
Net interest income	505,166	343,392	260,125
Provision for loan losses	19,758	16,667	8,364
Net interest income after provision for loan losses	485,408	326,725	251,761
Noninterest income
Service charges on deposit accounts	50,792	46,128	42,054
Mortgage banking activity	119,409	53,654	48,535
Other service charges, commissions and fees	3,913	3,059	2,883
Net gain (loss) on securities	138	(37)	37
Gain on sale of SBA loans	6,058	2,728	4,590
Other noninterest income	17,803	12,880	6,358
Total noninterest income	198,113	118,412	104,457
Noninterest expense
Salaries and employee benefits	223,938	149,132	119,783
Occupancy and equipment	40,596	29,131	24,069
Advertising and marketing	7,927	5,571	5,131
Amortization of intangible assets	17,713	9,512	3,932
Data processing and communications expenses	38,513	30,385	27,869
Legal and other professional fees	10,634	6,386	15,355
Credit resolution-related expenses	4,082	4,016	3,493
Merger and conversion charges	73,105	20,499	915
FDIC insurance	1,945	3,408	3,078
Other noninterest expenses	53,484	35,607	28,311
Total noninterest expense	471,937	293,647	231,936
Income before income tax expense	211,584	151,490	124,282
Income tax expense	50,143	30,463	50,734
Net income	$ 161,441	$ 121,027	$ 73,548
Basic earnings per common share (in dollars per share)	$ 2.76	$ 2.81	$ 2.00
Diluted earnings per common share (in dollars per share)	$ 2.75	$ 2.80	$ 1.98
Weighted average common shares outstanding
Basic (in shares)	58,462	43,142	36,828
Diluted (in shares)	58,614	43,248	37,144