CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 9,362	$ 7,212
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Amortization and accretion of premiums and discounts on securities, net	718	111
Accretion of loan discounts, net	(1,251)	(1,217)
Amortization of deposit premiums	(215)	(349)
Amortization of core deposit intangibles	316	380
Amortization and accretion of borrowing and debt valuation allowance, net	105	105
Amortization of issuance costs of subordinated notes	36	36
Provision for loan losses	9,663	6,145
Depreciation	501	533
Net loss on sale of real estate acquired by foreclosure	0	163
Net loss on loans held-for-sale	0	138
Net gain on sale of guaranteed portion of loans	(941)	(1,927)
Originations of loans held-for-sale	10,361	0
Proceeds from sales of and principal collected on loans held-for-sale	10,997	10,761
Stock-based compensation expense	1,317	535
Deferred tax benefit	(3,135)	(1,987)
Decrease in accrued interest receivable and other assets, net	2,310	4,216
Increase in accrued interest payable and other liabilities, net	(3,380)	(2,218)
Net cash provided by operating activities	36,764	22,637
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from the maturities or calls and paydowns of available-for-sale securities	16,839	15,765
Purchases of available-for-sale securities	(44,961)	(298,454)
Proceeds from the maturities or calls and paydowns of held-to-maturity securities	696	1,659
Purchases of held-to-maturity securities	(2,488)	0
Proceeds from sales of guaranteed portion of loans	0	21,959
Proceeds from sales of real estate acquired by foreclosure	0	3,701
Purchases of Federal Home Loan Bank of Dallas stock, net of redemptions	58	(394)
Purchases of Federal Reserve Bank stock	(72)	(14)
Net increase in loans held for investment	32,028	57,027
Investment in construction of premises and purchases of other fixed assets	(193)	(193)
Net cash provided by (used in) investing activities	1,907	(198,944)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in deposit accounts	56,799	41,787
Net decrease (increase) in securities sold under agreements to repurchase	(225)	823
Net proceeds (repayments) of other short-term borrowed funds	(95,000)	0
Proceeds from issuance of common stock due to exercise of stock options	1,218	271
Net cash (used in) provided by financing activities	(37,208)	42,881
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	1,463	(133,426)
CASH AND CASH EQUIVALENTS:
Beginning of period	140,681	389,007
End of period	142,144	255,581
NONCASH ACTIVITIES:
Noncash investing and financing activities - acquisition of real estate through foreclosure of collateral	0	5,270
Transfer of loans to held-for-sale	0	4,260
SUPPLEMENTAL INFORMATION:
Interest paid	8,191	6,880
Securities transferred from available-for-sale to held-to-maturity	$ 50,031	$ 0