CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 42,865	$ 29,202	$ 22,141
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	5,614	5,076	3,773
Amortization of premiums and discounts on securities, net	3,977	7,559	3,920
Other amortization and accretion, net	(697)	(2,238)	(1,601)
Stock based compensation	5,267	4,154	2,859
Origination of loans designated for sale	(213,027)	(175,842)	(206,199)
Sale of loans designated for sale	211,091	190,843	199,425
Provision for loan losses	5,648	2,411	2,644
Deferred income taxes	35,827	14,206	12,888
Gains on sale of securities	(86)	(368)	(161)
Gain on sale of VISA Class B stock	(15,153)	0	0
Gains on sale of loans	(7,038)	(6,335)	(5,146)
Losses (gains) on sale and write-downs of other real estate owned	(711)	(509)	239
Losses on disposition of fixed assets	2,270	2,442	183
Changes in operating assets and liabilities, net of effects from acquired companies:
Net increase in other assets	(5,506)	(11,573)	(4,828)
Net increase (decrease) in other liabilities	(21,432)	2,979	(628)
Net cash provided by operating activities	48,909	62,007	29,509
CASH FLOWS FROM INVESTING ACTIVITIES
Maturities and repayments of securities available for sale	211,173	127,879	118,493
Maturities and repayments of securities held for investment	86,460	48,705	28,629
Proceeds from sale of securities available for sale	235,613	40,421	60,314
Purchases of securities available for sale	(371,926)	(297,719)	(159,616)
Purchases of securities held for investment	(131,439)	(218,654)	(24,366)
Maturities of time deposits with other banks	4,720	0	0
Net new loans and principal repayments	(328,868)	(396,862)	(224,391)
Proceeds from the sale of portfolio loans	106,815	71,433	525
Purchases of loans held for investment	(55,352)	(64,925)	0
Proceeds from the sale of other real estate owned	6,069	7,952	5,758
Proceeds from sale of Federal Home Loan Bank (FHLB) and Federal Reserve Bank Stock	48,295	9,350	7,427
Purchase of FHLB and Federal Reserve Bank Stock	(42,680)	(28,857)	(7,510)
Purchase of VISA Class B stock	(6,180)	0	0
Redemption of bank owned life insurance	3,609	0	0
Purchase of bank owned life insurance	(30,000)	(40,000)	0
Net cash from bank acquisitions	23,825	235,546	32,927
Additions to bank premises and equipment	(5,710)	(6,054)	(9,091)
Net cash used in investing activities	(245,576)	(511,785)	(170,901)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase in deposits	333,049	27,320	240,086
Net increase in federal funds purchased and repurchase agreements	11,892	32,196	16,707
Net increase (decrease) in FHLB borrowings	(204,000)	415,000	(80,000)
Early redemption of FHLB borrowings	0	(50,000)	0
Stock based employee benefit plans	(55)	(1,161)	127
Issuance of common stock, net of related expense	55,641	0	0
Dividends paid	0	0	0
Net cash provided by financing activities	196,527	423,355	176,920
Net increase (decrease) in cash and cash equivalents	(140)	(26,423)	35,528
Cash and cash equivalents at beginning of year	109,644	136,067	100,539
Cash and cash equivalents at end of year	109,504	109,644	136,067
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	15,125	7,855	6,636
Cash paid during the period for income taxes	400	703	575
Supplemental disclosure of non cash investing activities:
Transfer from loans to other real estate owned	1,774	3,009	4,946
Transfer from bank premises to other real estate owned	$ 1,212	$ 7,708	$ 309