Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 42,024,000	$ 31,274,000	$ 31,913,000
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	9,766,000	10,358,000	9,576,000
Accretion of acquired loans	(1,373,000)	(2,338,000)	(4,925,000)
Provision for loan losses	1,100,000	2,950,000	2,900,000
Deferred income tax expense (benefit)	(372,000)	831,000	(812,000)
Stock-based compensation expense	2,410,000	1,981,000	1,459,000
Stock grants to directors for retainer fee	441,000	363,000	327,000
Proceeds from sales of mortgage loans held for sale	101,146,000	111,311,000	114,757,000
Origination of mortgage loans held for sale	(96,179,000)	(108,857,000)	(110,778,000)
Net gain on sales of mortgage loans held for sale	(3,536,000)	(3,972,000)	(3,699,000)
Gain on trust preferred securities repurchase	0	0	(2,970,000)
Net gain from sales and valuation write-downs of foreclosed assets	(169,000)	(319,000)	(520,000)
Net (gain) loss from sales and valuation write-downs of former bank premises	(78,000)	133,000	35,000
Net loss from sales and disposals of premises and equipment	134,000	71,000	174,000
Net (gain) loss from sales of available for sale securities	0	(37,000)	1,000
Earnings on bank owned life insurance	(1,287,000)	(2,731,000)	(1,264,000)
Net change in:
Accrued interest receivable	(1,126,000)	(1,056,000)	122,000
Other assets	(2,193,000)	(354,000)	(648,000)
Accrued interest and other liabilities	11,029,000	(943,000)	(1,046,000)
Net cash from operating activities	61,737,000	38,665,000	34,602,000
Cash flows from investing activities
Purchases of securities available for sale	(48,664,000)	(67,027,000)	(164,336,000)
Proceeds from maturities, calls and repayments of securities available for sale	40,308,000	52,504,000	172,173,000
Proceeds from sales of securities available for sale	0	7,619,000	264,000
Purchases of Federal Home Loan Bank stock	(4,986,000)	(3,010,000)	(459,000)
Loan originations and payments, net	(193,556,000)	(178,373,000)	(97,282,000)
Purchases of bank owned life insurance	0	(1,500,000)	(7,000,000)
Proceeds from bank owned life insurance cash value release and death benefits	0	2,720,000	0
Purchases of premises and equipment, net	(6,318,000)	(5,423,000)	(2,025,000)
Proceeds from sales of former bank premises	1,964,000	25,000	45,000
Proceeds from sales of foreclosed assets	772,000	993,000	2,059,000
Net cash for investing activities	(210,480,000)	(191,472,000)	(96,561,000)
Cash flows from financing activities
Net decrease in time deposits	(30,091,000)	(55,839,000)	(20,854,000)
Net (decrease) increase in all other deposits	(28,566,000)	203,219,000	120,457,000
Net decrease in securities sold under agreements to repurchase	(15,229,000)	(12,962,000)	(23,061,000)
Proceeds from Federal Home Loan Bank advances	160,000,000	90,000,000	110,000,000
Maturities of Federal Home Loan Bank advances	(30,000,000)	(45,000,000)	(3,000,000)
Proceeds from stock option exercises, net of cashless exercises	108,000	318,000	978,000
Employee stock purchase plan	52,000	46,000	36,000
Dividend reinvestment plan	1,165,000	1,576,000	1,601,000
Repurchase of common stock	(5,943,000)	0	(3,732,000)
Repurchase of trust preferred securities	0	0	(8,030,000)
Payment of cash dividends to common shareholders	(27,500,000)	(12,046,000)	(18,731,000)
Net cash from financing activities	23,996,000	169,312,000	155,664,000
Net change in cash and cash equivalents	(124,747,000)	16,505,000	93,705,000
Cash and cash equivalents at beginning of period	200,101,000	183,596,000	89,891,000
Cash and cash equivalents at end of period	75,354,000	200,101,000	183,596,000
Supplemental disclosures of cash flows information
Interest	21,569,000	15,468,000	12,477,000
Federal income taxes	10,075,000	14,225,000	15,125,000
Transfers from loans to foreclosed assets	744,000	887,000	414,000
Transfers from bank premises to other real estate owned	$ 296,000	$ 1,736,000	$ 381,000