Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Interest and fees on loans	$ 270,887	$ 218,659	$ 171,567
Interest on taxable securities	20,154	17,824	16,134
Interest on nontaxable securities	1,581	1,722	1,869
Interest on deposits in other banks	1,725	827	790
Interest on federal funds sold	0	33	33
Total interest income	294,347	239,065	190,393
Interest expense
Interest on deposits	19,877	12,410	9,752
Interest on other borrowings	14,345	7,284	5,104
Total interest expense	34,222	19,694	14,856
Net interest income	260,125	219,371	175,537
Provision for loan losses	8,364	4,091	5,264
Net interest income after provision for loan losses	251,761	215,280	170,273
Noninterest income
Service charges on deposit accounts	42,054	42,745	34,465
Mortgage banking activity	48,535	48,298	36,800
Other service charges, commissions and fees	2,872	3,575	3,754
Net gains on sales of securities	37	94	137
Gain on sale of SBA loans	4,590	3,974	4,522
Other noninterest income	6,369	7,115	5,908
Total noninterest income	104,457	105,801	85,586
Noninterest expense
Salaries and employee benefits	120,016	106,837	94,003
Occupancy and equipment	24,069	24,397	21,195
Advertising and marketing	5,131	4,181	3,312
Amortization of intangible assets	3,932	4,376	3,741
Data processing and communications expenses	27,869	24,591	19,849
Legal and other professional fees	15,355	9,885	3,448
Credit resolution-related expenses	3,493	6,172	17,707
Merger and conversion charges	915	6,376	7,980
FDIC insurance	3,078	3,712	3,475
Other noninterest expenses	28,078	25,308	24,405
Total noninterest expense	231,936	215,835	199,115
Income before income tax expense	124,282	105,246	56,744
Income tax expense	(50,734)	(33,146)	(15,897)
Net income	$ 73,548	$ 72,100	$ 40,847
Basic earnings per common share (in dollars per share)	$ 2.00	$ 2.10	$ 1.29
Diluted earnings per common share (in dollars per share)	1.98	2.08	1.27
Dividends declared per common share (in dollars per share)	$ 0.40	$ 0.30	$ 0.20
Weighted average common shares outstanding
Basic (in shares)	36,828	34,347	31,762
Diluted (in shares)	37,144	34,702	32,127