Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Operating activities:
Net income	$ 10,602	$ 10,109	$ 21,393	$ 19,944
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	600	750	1,500	1,250	$ 3,000
Depreciation, amortization and accretion, net			4,399	5,292
Deferred income tax provision			(517)	447
Gain on sales of mortgage loans held for sale			(963)	(1,103)
Origination of mortgage loans held for sale			(49,168)	(57,433)
Proceeds from sale of mortgage loans held for sale			50,289	58,931
Bank owned life insurance income	(556)	(220)	(760)	(441)
Loss (gain) on the sale of other real estate			64	(443)
Stock compensation expense			1,342	1,073
Excess tax benefits from share-based compensation arrangements			(1,120)	(520)
Decrease in accrued interest receivable and other assets			(4,015)	(5,246)
Increase in accrued interest payable and other liabilities			6,883	12,321
Net cash provided by operating activities			29,327	34,072
Investing activities:
Purchases of securities available for sale			(251,196)	(227,714)
Proceeds from sale of securities available for sale
Proceeds from maturities of securities available for sale			245,010	232,825
Purchase of Federal Home Loan Bank stock			(1,319)
Net increase in loans			(4,685)	(144,605)
Purchases of premises and equipment			(839)	(4,660)
Proceeds from disposal of premises and equipment			207
Proceeds from mortality benefit of bank owned life insurance			970
Proceeds from sale of foreclosed assets			1,784	1,401
Net cash used in investing activities			(10,068)	(142,753)
Financing activities:
Net decrease in deposits			(42,002)	(21,754)
Net increase in securities sold under agreements to repurchase and federal funds purchased			111,518	84,588
Proceeds from Federal Home Loan Bank advances			60,000	160,000
Repayments of Federal Home Loan Bank advances			(60,642)	(160,466)
Proceeds (used for) and received from settlement of stock awards			(216)	1,045
Excess tax benefits from share-based compensation arrangements				520
Common stock repurchases			(1,946)	(1,083)
Cash dividends paid			(8,819)	(7,768)
Net cash provided by financing activities			57,893	55,082
Net increase (decrease) in cash and cash equivalents			77,152	(53,599)
Cash and cash equivalents at beginning of period			47,973	103,833	103,833
Cash and cash equivalents at end of period	$ 125,125	$ 50,234	125,125	50,234	$ 47,973
Supplemental cash flow information:
Income tax payments			4,473	5,490
Cash paid for interest			3,187	2,438
Supplemental non-cash activity:
Transfers from loans to other real estate owned				$ 1,511