Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income	$ 49,456,000	$ 42,024,000	$ 31,274,000
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	9,553,000	9,766,000	10,358,000
Accretion of acquired loans	(686,000)	(1,373,000)	(2,338,000)
Provision for loan losses	1,750,000	1,100,000	2,950,000
Deferred income tax expense (benefit)	26,000	(372,000)	831,000
Stock-based compensation expense	2,931,000	2,410,000	1,981,000
Stock grants to directors for retainer fee	375,000	441,000	363,000
Proceeds from sales of mortgage loans held for sale	261,021,000	101,146,000	111,311,000
Origination of mortgage loans held for sale	(256,767,000)	(96,179,000)	(108,857,000)
Net gain on sales of mortgage loans held for sale	(8,108,000)	(3,536,000)	(3,972,000)
Net gain from sales and valuation write-downs of foreclosed assets	(254,000)	(169,000)	(319,000)
Net (gain) loss from sale and write-downs on former bank premises	(436,000)	(78,000)	133,000
Net loss from sales and disposals of premises and equipment	294,000	134,000	71,000
Net gain from sales of available for sale securities	0	0	(37,000)
Earnings on bank owned life insurance	(3,886,000)	(1,287,000)	(2,731,000)
Net change in:
Accrued interest receivable	(48,000)	(1,126,000)	(1,056,000)
Other assets	(7,636,000)	(2,193,000)	(354,000)
Accrued interest and other liabilities	(2,818,000)	11,029,000	(943,000)
Net cash from operating activities	44,767,000	61,737,000	38,665,000
Cash flows from investing activities
Purchases of securities available for sale	(62,084,000)	(48,664,000)	(67,027,000)
Proceeds from maturities, calls and repayments of securities available for sale	79,478,000	40,308,000	52,504,000
Proceeds from sales of securities available for sale	0	0	7,619,000
Purchases of Federal Home Loan Bank stock	(1,980,000)	(4,986,000)	(3,010,000)
Loan originations and payments, net	(99,620,000)	(193,556,000)	(178,373,000)
Purchases of bank owned life insurance	(4,500,000)	0	(1,500,000)
Proceeds from bank owned life insurance cash value release and death benefits	7,708,000	0	2,720,000
Purchases of premises and equipment, net	(13,484,000)	(6,318,000)	(5,423,000)
Proceeds from sales of former bank premises	854,000	1,964,000	25,000
Proceeds from sales of foreclosed assets	790,000	772,000	993,000
Net cash for investing activities	(92,838,000)	(210,480,000)	(191,472,000)
Cash flows from financing activities
Net (decrease) increase in time deposits	170,921,000	(30,091,000)	(55,839,000)
Net (decrease) increase in all other deposits	55,755,000	(28,566,000)	203,219,000
Net decrease in securities sold under agreements to repurchase	(844,000)	(15,229,000)	(12,962,000)
Proceeds from Federal Home Loan Bank advances	44,000,000	160,000,000	90,000,000
Maturities of Federal Home Loan Bank advances	(40,000,000)	(30,000,000)	(45,000,000)
Proceeds from stock option exercises, net of cashless exercises	128,000	108,000	318,000
Employee stock purchase plan	50,000	52,000	46,000
Dividend reinvestment plan	729,000	1,165,000	1,576,000
Repurchases of common stock	(7,183,000)	(5,943,000)	0
Payment of cash dividends to common shareholders	(17,108,000)	(27,500,000)	(12,046,000)
Net cash from financing activities	206,448,000	23,996,000	169,312,000
Net change in cash and cash equivalents	158,377,000	(124,747,000)	16,505,000
Cash and cash equivalents at beginning of period	75,354,000	200,101,000	183,596,000
Cash and cash equivalents at end of period	233,731,000	75,354,000	200,101,000
Supplemental disclosures of cash flows information
Interest	32,103,000	21,569,000	15,468,000
Federal income taxes	11,975,000	10,075,000	14,225,000
Transfers from loans to foreclosed assets	337,000	744,000	887,000
Transfers from bank premises to other real estate owned	$ 258,000	$ 296,000	$ 1,736,000