Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Cash Flows From Operating Activities
Net income	$ 21,991	$ 13,086	$ 65,394	$ 31,795
Reconciliation of net income to net cash (used) provided by operating activities:
Provision (reversal) for loan losses	87		(4,282)	723	$ 723
Net security premium amortization			2,184	2,165
Loan discount accretion			(5,982)	(5,073)
Purchase accounting accretion and amortization, net			(165)	(142)
Foreclosed property (gains) losses and write-downs, net			579	439
Loss (gain) on securities available for sale				235
Other losses (gains)			(811)	(493)
Decrease (increase) in net deferred loan fees			(1,475)	388
Depreciation of premises and equipment			4,420	4,023
Stock-based compensation expense			1,201	860
Amortization of intangible assets	1,656	902	5,073	2,509
Fees/gains from sale of presold mortgages and SBA loans			(11,004)	(7,362)
Origination of presold mortgages in process of settlement			(97,081)	(169,021)
Proceeds from sales of presold mortgages in process of settlement			105,506	165,341
Origination of SBA loans for sale			(162,782)	(54,714)
Proceeds from sales of SBA loans			130,460	44,259
Increase in accrued interest receivable			(888)	(642)
Increase in other assets			(893)	(13,112)
Increase in accrued interest payable			681	340
Decrease in other liabilities			(6,448)	(12,377)
Net cash provided (used) by operating activities			23,687	(9,859)
Cash Flows From Investing Activities
Purchases of securities available for sale			(48,975)	(35,034)
Purchases of securities held to maturity				(291)
Proceeds from maturities/issuer calls of securities available for sale			27,609	29,156
Proceeds from maturities/issuer calls of securities held to maturity			12,841	18,021
Proceeds from sales of securities available for sale				45,601
Purchases of Federal Reserve and Federal Home Loan Bank stock, net			(6,129)	(10,372)
Net increase in loans			(103,091)	(206,948)
Proceeds from sales of foreclosed real estate			6,829	6,468
Purchases of premises and equipment			(6,656)	(3,040)
Proceeds from sales of premises and equipment			2,739	114
Net cash received in acquisition				48,636
Net cash used by investing activities			(114,833)	(107,689)
Cash Flows From Financing Activities
Net increase in deposits			121,719	118,752
Net increase (decrease) in borrowings			(1,086)	106,980
Cash dividends paid - common stock			(8,308)	(5,617)
Proceeds from stock option exercises	0	0	324	287
Stock withheld for payment of taxes			(264)
Net cash provided by financing activities			112,385	220,402
Increase in cash and cash equivalents			21,239	102,854
Cash and cash equivalents, beginning of period			489,490	305,993	305,993
Cash and cash equivalents, end of period	$ 510,729	$ 408,847	510,729	408,847	$ 489,490
Cash paid during the period for:
Interest			15,750	8,115
Income taxes			17,333	15,275
Non-cash transactions:
Unrealized gain (loss) on securities available for sale, net of taxes			(7,839)	2,223
Foreclosed loans transferred to other real estate			$ 2,159	$ 3,897