CONDENSED CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2019	$ 215,125	$ 108,667	$ 323,792
Balance, shares at Dec. 31, 2019	17,434
Net Income		17,381	17,381
Dividend Reinvestment & Common Stock Purchase Plan	$ 608		608
Dividend Reinvestment & Common Stock Purchase Plan, shares	9
Restricted Stock Award, Net - Employees	$ 387		387
Restricted Stock Award, Net - Employees, shares	17
Restricted Stock Award - Board of Directors	$ 245		245
Restricted Stock Award - Board of Directors, shares	4
Cash Dividends on Common Stock		(8,942)	(8,942)
Cash Dividends on Preferred Stock		(60)	(60)
Common Stock Issuance Expenses		(38)	(38)
Balance at Jun. 30, 2020	$ 216,365	117,008	333,373
Balance, shares at Jun. 30, 2020	17,464
Balance at Mar. 31, 2020	$ 215,600	111,800	327,400
Balance, shares at Mar. 31, 2020	17,439
Net Income		9,713	9,713
Dividend Reinvestment & Common Stock Purchase Plan	$ 294		294
Dividend Reinvestment & Common Stock Purchase Plan, shares	4
Restricted Stock Award, Net - Employees	$ 226		226
Restricted Stock Award, Net - Employees, shares	17
Restricted Stock Award - Board of Directors	$ 245		245
Restricted Stock Award - Board of Directors, shares	4
Cash Dividends on Common Stock		(4,475)	(4,475)
Cash Dividends on Preferred Stock		(30)	(30)
Balance at Jun. 30, 2020	$ 216,365	117,008	333,373
Balance, shares at Jun. 30, 2020	17,464
Balance at Dec. 31, 2020	$ 217,451	128,757	346,208
Balance, shares at Dec. 31, 2020	17,473
Net Income		17,828	17,828
Dividend Reinvestment & Common Stock Purchase Plan	$ 596		596
Dividend Reinvestment & Common Stock Purchase Plan, shares	8
Restricted Stock Award, Net - Employees	$ (192)		(192)
Restricted Stock Award, Net - Employees, shares	6
Restricted Stock Award - Board of Directors	$ 245		245
Restricted Stock Award - Board of Directors, shares	3
Cash Dividends on Common Stock		(9,527)	(9,527)
Cash Dividends on Preferred Stock		(60)	(60)
Balance at Jun. 30, 2021	$ 218,100	136,998	355,098
Balance, shares at Jun. 30, 2021	17,490
Balance at Mar. 31, 2021	$ 217,977	130,873	348,850
Balance, shares at Mar. 31, 2021	17,478
Net Income		10,923	10,923
Dividend Reinvestment & Common Stock Purchase Plan	$ 272		272
Dividend Reinvestment & Common Stock Purchase Plan, shares	3
Restricted Stock Award, Net - Employees	$ (394)		(394)
Restricted Stock Award, Net - Employees, shares	6
Restricted Stock Award - Board of Directors	$ 245		245
Restricted Stock Award - Board of Directors, shares	3
Cash Dividends on Common Stock		(4,768)	(4,768)
Cash Dividends on Preferred Stock		(30)	(30)
Balance at Jun. 30, 2021	$ 218,100	$ 136,998	$ 355,098
Balance, shares at Jun. 30, 2021	17,490