Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - 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, 2019	$ 0	$ 305,035,000	$ 107,831,000	$ 3,695,000	$ 416,561,000
Employee stock purchase plan		25,000			25,000
Dividend reinvestment plan		404,000			404,000
Stock grants to directors for retainer fees		349,000			349,000
Stock-based compensation expense		1,366,000			1,366,000
Share repurchase program		(6,282,000)			(6,282,000)
Cash dividends			(8,962,000)		(8,962,000)
Net income			19,370,000		19,370,000
Change in net unrealized holding gain/(loss) on securities available for sale, net of tax effect				2,390,000	2,390,000
Balances at Jun. 30, 2020	0	300,897,000	118,239,000	6,085,000	425,221,000
Balances at Mar. 31, 2020	0	299,584,000	114,012,000	4,793,000	418,389,000
Employee stock purchase plan		11,000			11,000
Dividend reinvestment plan		212,000			212,000
Stock grants to directors for retainer fees		349,000			349,000
Stock-based compensation expense		741,000			741,000
Cash dividends			(4,471,000)		(4,471,000)
Net income			8,698,000		8,698,000
Change in net unrealized holding gain/(loss) on securities available for sale, net of tax effect				1,292,000	1,292,000
Balances at Jun. 30, 2020	0	300,897,000	118,239,000	6,085,000	425,221,000
Balances at Dec. 31, 2020	0	302,029,000	134,039,000	5,486,000	441,554,000
Employee stock purchase plan		22,000			22,000
Dividend reinvestment plan		411,000			411,000
Stock grants to directors for retainer fees		344,000			344,000
Stock-based compensation expense		1,277,000			1,277,000
Share repurchase program		(10,851,000)			(10,851,000)
Cash dividends			(9,220,000)		(9,220,000)
Net income			32,331,000		32,331,000
Change in net unrealized holding gain/(loss) on securities available for sale, net of tax effect				(3,980,000)	(3,980,000)
Balances at Jun. 30, 2021	0	293,232,000	157,150,000	1,506,000	451,888,000
Balances at Mar. 31, 2021	0	299,358,000	143,642,000	(1,757,000)	441,243,000
Employee stock purchase plan		11,000			11,000
Dividend reinvestment plan		198,000			198,000
Stock grants to directors for retainer fees		344,000			344,000
Stock-based compensation expense		634,000			634,000
Share repurchase program		(7,313,000)			(7,313,000)
Cash dividends			(4,583,000)		(4,583,000)
Net income			18,091,000		18,091,000
Change in net unrealized holding gain/(loss) on securities available for sale, net of tax effect				3,263,000	3,263,000
Balances at Jun. 30, 2021	$ 0	$ 293,232,000	$ 157,150,000	$ 1,506,000	$ 451,888,000