Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net income	$ 59,021,000	$ 44,138,000	$ 49,456,000
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	13,678,000	9,425,000	9,553,000
Accretion of acquired loans	(135,000)	(449,000)	(686,000)
Provision (benefit) for loan losses	(4,300,000)	14,050,000	1,750,000
Deferred income tax expense (benefit)	2,020,000	(4,141,000)	26,000
Stock-based compensation expense	3,784,000	2,325,000	2,931,000
Stock grants to directors for retainer fee	344,000	394,000	375,000
Proceeds from sales of mortgage loans held for sale	686,418,000	677,634,000	261,021,000
Origination of mortgage loans held for sale	(649,245,000)	(665,992,000)	(256,767,000)
Net gain on sales of mortgage loans held for sale	(30,402,000)	(29,541,000)	(8,108,000)
Net gain from sales and valuation write-downs of foreclosed assets	(78,000)	(325,000)	(254,000)
Net gain from sale and write-downs on former bank premises	(140,000)	(27,000)	(436,000)
Net loss from sales and disposals of premises and equipment	246,000	1,514,000	294,000
Earnings on bank owned life insurance	(1,164,000)	(1,214,000)	(3,886,000)
Gain on sale of branch	(1,058,000)	0	0
Net change in:
Accrued interest receivable	1,528,000	(917,000)	(48,000)
Other assets	(16,279,000)	(10,892,000)	(7,636,000)
Accrued interest and other liabilities	335,000	1,895,000	(2,818,000)
Net cash from operating activities	64,573,000	37,877,000	44,767,000
Cash flows from investing activities
Purchases of securities available for sale	(298,708,000)	(369,682,000)	(62,084,000)
Proceeds from maturities, calls and repayments of securities available for sale	80,432,000	321,164,000	79,478,000
Purchases of Federal Home Loan Bank stock	0	0	(1,980,000)
Loan originations and payments, net	(267,899,000)	(341,461,000)	(99,620,000)
Purchases of bank owned life insurance	(2,000,000)	(700,000)	(4,500,000)
Proceeds from bank owned life insurance cash value release and death benefits	0	0	7,708,000
Net cash transferred in branch sale	(2,679,000)	0	0
Net purchases of premises and equipment and lease activity	(5,602,000)	(8,989,000)	(13,484,000)
Proceeds from sales of former bank premises	753,000	162,000	854,000
Proceeds from sales of foreclosed assets	196,000	700,000	790,000
Net cash for investing activities	(495,507,000)	(398,806,000)	(92,838,000)
Cash flows from financing activities
Net (decrease) increase in time deposits	(120,512,000)	(99,294,000)	170,921,000
Net increase in all other deposits	806,796,000	820,463,000	55,755,000
Net (decrease) increase in securities sold under agreements to repurchase	79,098,000	15,690,000	(844,000)
Proceeds from Federal Home Loan Bank advances	0	60,000,000	44,000,000
Maturities of Federal Home Loan Bank advances	(20,000,000)	(20,000,000)	(40,000,000)
Net proceeds from subordinated notes issuance	73,635,000	0	0
Proceeds from stock option exercises, net of cashless exercises	50,000	3,000	128,000
Employee stock purchase plan	48,000	49,000	50,000
Dividend reinvestment plan	877,000	814,000	729,000
Repurchases of common stock	(21,380,000)	(6,591,000)	(7,183,000)
Payment of cash dividends to common shareholders	(18,524,000)	(17,930,000)	(17,108,000)
Net cash from financing activities	780,088,000	753,204,000	206,448,000
Net change in cash and cash equivalents	349,154,000	392,275,000	158,377,000
Cash and cash equivalents at beginning of period	626,006,000	233,731,000	75,354,000
Cash and cash equivalents at end of period	975,160,000	626,006,000	233,731,000
Supplemental disclosures of cash flows information
Interest	20,352,000	27,703,000	32,103,000
Federal income taxes	17,550,000	10,950,000	11,975,000
Noncash financing and investing activities:
Transfers from loans to foreclosed assets	30,000	146,000	337,000
Transfers from bank premises to other real estate owned	$ 0	$ 613,000	$ 258,000