Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 47,346	$ 46,432	$ 43,251
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,904	3,932	4,314
Deferred taxes	701	115	(1,048)
Stock-based compensation	458	783	852
Excess tax benefits of stock-based compensation	100	104	760
Provision for loan losses	7,872	8,650	8,755
Write-downs of other real estate owned and other repossessed assets	1,214	1,656	1,730
Gains on sale of mortgage loans held for sale	(1,831)	(1,978)	(1,468)
Securities (gains) losses	(522)	106	211
Gains on sale of assets, net	46	(321)	(73)
Proceeds from sale of mortgage loans held for sale	81,441	80,571	51,181
Funding of mortgage loans held for sale	(79,682)	(77,501)	(51,149)
Amortization of securities premiums and discounts, net	2,452	3,098	2,661
Change in cash surrender value of bank owned life insurance	(1,546)	(1,638)	(1,506)
Mortgage servicing rights:
Fair value adjustments	324	289	830
New servicing assets created	(521)	(557)	(374)
Changes in:
Other assets	(3,205)	(6,274)	(60)
Other liabilities	2,874	(2,488)	(1,339)
Net cash provided by operating activities	61,425	54,979	57,528
Certificates of deposit in other banks:
Purchase of certificates of deposit	0	0	(245)
Maturity of certificates of deposit	2,852	4,365	1,616
Securities available-for-sale (AFS):
Purchase of AFS securities	(176,236)	(81,456)	(217,949)
Proceeds from sales of AFS securities	54,446	44,198	135,411
Proceeds from prepayments, calls, and maturities of AFS securities	104,302	79,068	63,023
Securities held-to-maturity (HTM):
Proceeds from prepayments and maturities of HTM securities	795	1	0
Change in loans, net	(74,379)	(161,702)	(132,906)
Purchase of premises and equipment	(3,498)	(2,246)	(2,081)
Proceeds from sale of premises and equipment	10	239	82
Redemption of stock by FHLB	0	0	7,746
Additional investment in Federal Reserve Bank stock	0	(18)	(1)
Cancellation of Federal Reserve Bank stock	0	0	18
Proceeds from sale of other real estate owned and repossessed assets	5,601	9,287	6,714
Additional investment in other real estate owned and repossessed assets	0	(85)	0
Additional investment in bank owned life insurance	0	0	(5,504)
Net cash used in investing activities	(86,107)	(108,349)	(144,076)
Cash flows from financing activities:
Change in deposits, net	100,526	106,525	19,183
Change in repurchase agreements and federal funds purchased, net	1,060	8,594	25,695
Advances from Federal Home Loan Bank	50,000	170,000	60,000
Payments on advances from Federal Home Loan Bank	(150,112)	(130,114)	(116)
Issuance of common stock	2,985	2,082	1,992
Repurchase of common stock	(382)	(189)	0
Excess tax benefits of stock-based compensation	(100)	(104)	(760)
Dividends paid	(22,190)	(21,330)	(20,570)
Net cash provided by (used in) financing activities	(18,213)	135,464	85,424
Net increase (decrease) in cash and cash equivalents	(42,895)	82,094	(1,124)
Cash and cash equivalents at beginning of year	187,611	105,517	106,641
Cash and cash equivalents at end of year	144,716	187,611	105,517
Supplemental disclosures:
Income taxes paid	19,244	20,527	15,818
Interest paid	13,426	11,609	11,922
Non-cash activities:
Loans to facilitate the sale of other real estate owned and repossessed assets	3,964	4,343	6,168
Common stock dividends accrued, paid in subsequent quarter	209	239	216
Real estate acquired in settlement of loans	$ 5,900	$ 18,557	$ 12,199