Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net income		$ 66,067	$ 55,517	$ 38,043
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses		1,000	2,705	2,550
Depreciation, amortization and accretion, net		4,880	5,782	13,640
Deferred income tax (benefit) expense		(5,852)	(268)	3,971
Loss on sale of securities available for sale		0	0	232
Gain on other investment activities		0	(113)	(92)
Gain on sales of mortgage loans held for sale		(1,907)	(1,443)	(1,989)
Origination of mortgage loans held for sale		(108,020)	(71,807)	(97,623)
Proceeds from sale of mortgage loans held for sale		102,854	74,539	99,861
Bank owned life insurance income	[1]	(1,031)	(1,129)	(1,159)
Loss on the disposal of premises and equipment		372	56	0
Loss (gain) on the sale of other real estate owned		7	(102)	(39)
Stock compensation expense		3,578	4,027	2,892
Excess tax benefits from share-based compensation arrangements		(812)	(549)	(1,463)
Net change in accrued interest receivable and other assets		(2,786)	(582)	(13,848)
Net change in accrued interest payable and other liabilities		85	(744)	8,700
Net cash provided by operating activities		58,436	65,889	53,676
Investing activities:
Purchases of securities available for sale		(702,441)	(768,407)	(661,086)
Proceeds from sales of securities available for sale		12,427	0	421
Proceeds from maturities and paydowns of securities available for sale		678,039	901,512	652,411
Purchase of Federal Home Loan Bank stock		0	(2,724)	(2,254)
Proceeds from redemption of Federal Home Loan Bank stock		591	0	955
Proceeds from redemption of acquired Federal Reserve Bank stock		490	0	0
Proceeds from redemption of interest bearing due from banks		1,761	0	0
Net change in loans		(131,734)	(137,835)	(105,867)
Purchases of premises and equipment		(5,098)	(7,057)	(2,786)
Proceeds from sales of premises and equipment		2,907	230	0
Proceeds from surrender of acquired bank owned life insurance		3,431	0	0
Proceeds from bank owned life insurance mortality benefit		1,878	0	977
Other investment activities		(2,766)	(1,184)	92
Proceeds from sales of other real estate owned		2,028	3,895	2,432
Cash for acquisition, net of cash acquired		(24,686)	0	0
Net cash used in investing activities		(163,173)	(11,570)	(114,705)
Financing activities:
Net change in deposits		213,913	216,061	57,747
Net change in securities sold under agreements to repurchase and federal funds purchased		(5,125)	(185,484)	116,856
Proceeds from Federal Home Loan Bank advances		120,000	120,000	120,000
Repayments of Federal Home Loan Bank advances		(131,726)	(121,281)	(121,617)
Repayment of acquired bank holding company line of credit		(2,300)	0	0
Redemption of acquired bank subordinated debentures		(3,609)	0	0
Repurchase of common stock		(11,817)	(2,004)	(2,389)
Share repurchases related to compensation plans		(272)	(154)	(216)
Cash dividends paid		(23,542)	(21,766)	(18,077)
Net cash provided by financing activities		155,522	5,372	152,304
Net change in cash and cash equivalents		50,785	59,691	91,275
Cash and cash equivalents at beginning of period		198,939	139,248	47,973
Cash and cash equivalents at end of period		249,724	198,939	139,248
Supplemental cash flow information:
Income tax payments, net of refunds		13,938	7,227	15,838
Cash paid for interest		22,666	14,827	7,158
Supplemental non-cash activity:
Initial recognition of right-of-use lease assets		16,747	0	0
Initial recognition operating lease liabilities		18,067	0	0
Loans purchased and not settled		0	4,992	0
Transfers from loans to real estate acquired in settlement of loans		1,160	2,170	0
Fair value of assets acquired		204,613	0	0
Cash paid in acquisition		28,000	0	0
Liabilities assumed		$ 176,613	$ 0	$ 0

[1] Outside of the scope of ASC 606