Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income
Interest and fees on loans	$ 378,209	$ 270,887	$ 218,659
Interest on taxable securities	29,006	20,154	17,824
Interest on nontaxable securities	900	1,581	1,722
Interest on deposits in other banks	4,984	1,725	827
Interest on federal funds sold	227	0	33
Total interest income	413,326	294,347	239,065
Interest expense
Interest on deposits	49,054	19,877	12,410
Interest on other borrowings	20,880	14,345	7,284
Total interest expense	69,934	34,222	19,694
Net interest income	343,392	260,125	219,371
Provision for loan losses	16,667	8,364	4,091
Net interest income after provision for loan losses	326,725	251,761	215,280
Noninterest income
Service charges on deposit accounts	46,128	42,054	42,745
Mortgage banking activity	51,292	48,535	48,298
Other service charges, commissions and fees	3,003	2,872	3,575
Net gain (loss) on securities	(37)	37	94
Gain on sale of SBA loans	2,728	4,590	3,974
Other noninterest income	15,298	6,369	7,115
Total noninterest income	118,412	104,457	105,801
Noninterest expense
Salaries and employee benefits	149,293	120,016	106,837
Occupancy and equipment	29,131	24,069	24,397
Advertising and marketing	5,571	5,131	4,181
Amortization of intangible assets	9,512	3,932	4,376
Data processing and communications expenses	30,385	27,869	24,591
Legal and other professional fees	6,386	15,355	9,885
Credit resolution-related expenses	4,016	3,493	6,172
Merger and conversion charges	20,499	915	6,376
FDIC insurance	3,408	3,078	3,712
Other noninterest expenses	35,446	28,078	25,308
Total noninterest expense	293,647	231,936	215,835
Income before income tax expense	151,490	124,282	105,246
Income tax expense	(30,463)	(50,734)	(33,146)
Net income	$ 121,027	$ 73,548	$ 72,100
Basic earnings per common share (in dollars per share)	$ 2.81	$ 2.00	$ 2.10
Diluted earnings per common share (in dollars per share)	2.80	1.98	2.08
Dividends declared per common share (in dollars per share)	$ 0.40	$ 0.40	$ 0.30
Weighted average common shares outstanding
Basic (in shares)	43,142	36,828	34,347
Diluted (in shares)	43,248	37,144	34,702