Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 55,517	$ 38,043	$ 41,027
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,705	2,550	3,000
Depreciation, amortization and accretion, net	5,782	13,640	11,142
Deferred income tax (benefit) expense	(268)	3,971	276
Loss on sale of securities available for sale		232
Gain on sales of mortgage loans held for sale	(1,443)	(1,989)	(2,482)
Origination of mortgage loans held for sale	(71,807)	(97,623)	(123,347)
Proceeds from sale of mortgage loans held for sale	74,539	99,861	129,416
Bank owned life insurance income	(1,129)	(1,159)	(871)
Gain on other investment activities	(113)	(92)	(588)
Net realized gain on sale of OREO	(102)	(39)	(409)
Loss on the disposal of premises and equipment	56		202
Stock-based compensation expense	4,027	2,892	2,473
Excess tax benefits from stock-based compensation arrangements	(549)	(1,463)	(1,705)
Net change in accrued interest receivable and other assets	(582)	(13,848)	(7,438)
Net change in accrued interest payable and other liabilities	(744)	8,700	12,566
Net cash provided by operating activities	65,889	53,676	63,262
Investing activities
Purchases of securities available for sale	(768,407)	(661,086)	(478,798)
Proceeds from sale of securities available for sale	0	421	0
Proceeds from maturities and paydowns of securities available for sale	901,512	652,411	468,271
Purchase of Federal Home Loan Bank Stock	(2,724)	(2,254)
Proceeds from sale of Federal Home Loan Bank stock		955
Net increase in loans	(137,835)	(105,867)	(275,718)
Purchases of premises and equipment	(7,057)	(2,786)	(6,327)
Proceeds from disposal of equipment	230		66
Proceeds from mortality benefit of bank owned life insurance		977
Proceeds from sale of OREO	3,895	2,432	1,826
Other investment activities	(1,184)	92	1,108
Net cash used in investing activities	(11,570)	(114,705)	(289,572)
Financing activities
Net change in deposits	216,061	57,747	148,846
Net change in securities sold under agreements to repurchase and federal funds purchased	(185,484)	116,856	27,966
Proceeds from Federal Home Loan Bank advances	120,000	120,000	289,000
Repayments of Federal Home Loan Bank advances	(121,281)	(121,617)	(281,393)
Proceeds (used for) and received from settlement of stock awards	(154)	(216)	2,337
Excess tax benefits from stock-based compensation arrangements			1,705
Common stock repurchases	(2,004)	(2,389)	(1,918)
Cash dividends paid	(21,766)	(18,077)	(16,093)
Net cash provided by financing activities	5,372	152,304	170,450
Net increase (decrease) in cash and cash equivalents	59,691	91,275	(55,860)
Cash and cash equivalents at beginning of period	139,248	47,973	103,833
Cash and cash equivalents at end of period	198,939	139,248	47,973
Supplemental cash flow information:
Income tax payments	7,227	15,838	12,860
Cash paid for interest	14,827	7,158	4,901
Supplemental non-cash activity:
Transfers from loans to foreclosed assets	2,170		1,916
Loans purchased not settled	$ 4,992