Consolidated Statements of Changes in Shareholders' Equity - USD ($)	Preferred Stock [Member]	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balances at Dec. 31, 2018	$ 0	$ 308,005,000	$ 75,483,000	$ (8,239,000)	$ 375,249,000
Employee stock purchase plan		50,000			50,000
Dividend reinvestment plan		729,000			729,000
Stock option exercises		128,000			128,000
Stock grants to directors for retainer fees		375,000			375,000
Stock-based compensation expense		2,931,000			2,931,000
Share repurchase program		(7,183,000)			(7,183,000)
Cash dividends			(17,108,000)		(17,108,000)
Net income			49,456,000		49,456,000
Change in net unrealized gain/(loss) on securities available for sale, net of tax effect				11,934,000	11,934,000
Balances at Dec. 31, 2019	0	305,035,000	107,831,000	3,695,000	416,561,000
Employee stock purchase plan		49,000			49,000
Dividend reinvestment plan		814,000			814,000
Stock option exercises		3,000			3,000
Stock grants to directors for retainer fees		394,000			394,000
Stock-based compensation expense		2,325,000			2,325,000
Share repurchase program		(6,591,000)			(6,591,000)
Cash dividends			(17,930,000)		(17,930,000)
Net income			44,138,000		44,138,000
Change in net unrealized gain/(loss) on securities available for sale, net of tax effect				1,791,000	1,791,000
Balances at Dec. 31, 2020	0	302,029,000	134,039,000	5,486,000	441,554,000
Employee stock purchase plan		48,000			48,000
Dividend reinvestment plan		877,000			877,000
Stock option exercises		50,000			50,000
Stock grants to directors for retainer fees		344,000			344,000
Stock-based compensation expense		3,784,000			3,784,000
Share repurchase program		(21,380,000)			(21,380,000)
Cash dividends			(18,524,000)		(18,524,000)
Net income			59,021,000		59,021,000
Change in net unrealized gain/(loss) on securities available for sale, net of tax effect				(9,215,000)	(9,215,000)
Balances at Dec. 31, 2021	$ 0	$ 285,752,000	$ 174,536,000	$ (3,729,000)	$ 456,559,000