CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INTEREST INCOME
Loans	$ 415,410	$ 251,027	$ 157,935
Investment securities and other interest-earning assets	33,013	18,978	8,670
Total interest income	448,423	270,005	166,605
INTEREST EXPENSE
Deposits	37,653	13,371	8,391
FHLB advances and other borrowings	11,343	4,411	1,295
Subordinated debentures	6,716	4,721	3,844
Total interest expense	55,712	22,503	13,530
Net interest income before provision for credit losses	392,711	247,502	153,075
Provision for credit losses	8,253	8,432	9,296
Net interest income after provision for credit losses	384,458	239,070	143,779
NONINTEREST INCOME
Loan servicing fees	1,445	787	1,032
Earnings on bank-owned life insurance	3,427	2,279	1,353
Net gain from sales of loans	10,759	12,468	9,539
Net gain from sales of investment securities	1,399	2,737	1,797
Other income	3,641	5,680	2,639
Total noninterest income	31,027	31,114	19,602
NONINTEREST EXPENSE
Compensation and benefits	129,886	84,138	52,836
Premises and occupancy	24,544	14,742	9,838
Data processing	13,412	8,206	4,261
Other real estate owned operations, net	4	72	385
FDIC insurance premiums	3,002	2,151	1,545
Legal, audit and professional expense	10,040	6,101	3,041
Marketing expense	6,151	4,436	3,981
Office, telecommunications and postage expense	5,312	3,117	2,107
Loan expense	3,370	3,299	2,191
Deposit expense	9,916	6,240	4,904
Merger-related expense	18,454	21,002	4,388
CDI amortization	13,594	6,144	2,039
Other expense	12,220	8,310	6,547
Total noninterest expense	249,905	167,958	98,063
Net income before income taxes	165,580	102,226	65,318
Income tax	42,240	42,126	25,215
Net income	$ 123,340	$ 60,100	$ 40,103
EARNINGS PER SHARE
Basic (in dollars per share)	$ 2.29	$ 1.59	$ 1.49
Diluted (in dollars per share)	$ 2.26	$ 1.56	$ 1.46
WEIGHTED AVERAGE SHARES OUTSTANDING
Basic (in shares)	53,963,047	37,705,556	26,931,634
Diluted (in shares)	54,613,057	38,511,261	27,439,159
Service charges on deposit accounts
NONINTEREST INCOME
Noninterest income	$ 5,128	$ 3,273	$ 1,459
Other service fee income
NONINTEREST INCOME
Noninterest income	902	1,847	1,516
Debit card interchange fee income
NONINTEREST INCOME
Noninterest income	$ 4,326	$ 2,043	$ 267