CONDENSED CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2018	$ 157,354	$ 91,433	$ 248,787
Balance, shares at Dec. 31, 2018	16,403,000
Net Income		25,818	25,818
Dividend Reinvestment & Common Stock Purchase Plan	$ 12,449		$ 12,449
Dividend Reinvestment & Common Stock Purchase Plan, shares	222,000		221,558
Restricted Stock Award, Net - Employees	$ 679		$ 679
Restricted Stock Award, Net - Employees, shares	18,000
Stock Award - Board Of Directors	$ 196		196
Stock Award - Board Of Directors, shares	4,000
Shares Forefeited	$ (466)		(466)
Shares Forfeited, shares	(18,000)
Conversion of Convertible Preferred Stock	$ 350		350
Conversion of Convertible Preferred Stock, shares	41,000
Cash Dividends on Common Stock		(11,893)	(11,893)
Cash Dividends on Preferred Stock		(102)	(102)
Common Stock Expenses		(23)	(23)
Balance at Sep. 30, 2019	$ 170,562	105,233	275,795
Balance, shares at Sep. 30, 2019	16,670,000
Balance at Jun. 30, 2019	$ 165,138	98,146	263,284
Balance, shares at Jun. 30, 2019	16,554,000
Net Income		11,119	11,119
Dividend Reinvestment & Common Stock Purchase Plan	$ 5,368		5,368
Dividend Reinvestment & Common Stock Purchase Plan, shares	92,000
Restricted Stock Award, Net - Employees	$ 172		172
Restricted Stock Award, Net - Employees, shares	1,000
Shares Forefeited	$ (466)		(466)
Shares Forfeited, shares	(18,000)
Conversion of Convertible Preferred Stock	$ 350		350
Conversion of Convertible Preferred Stock, shares	41,000
Cash Dividends on Common Stock		(3,987)	(3,987)
Cash Dividends on Preferred Stock		(30)	(30)
Common Stock Expenses		(15)	(15)
Balance at Sep. 30, 2019	$ 170,562	105,233	275,795
Balance, shares at Sep. 30, 2019	16,670,000
Balance at Dec. 31, 2019	$ 215,125	108,667	323,792
Balance, shares at Dec. 31, 2019	17,434,000
Net Income		30,118	30,118
Dividend Reinvestment & Common Stock Purchase Plan	$ 921		$ 921
Dividend Reinvestment & Common Stock Purchase Plan, shares	14,000		14,223
Restricted Stock Award, Net - Employees	$ 575		$ 575
Restricted Stock Award, Net - Employees, shares	17,000
Restricted Stock Award - Board of Directors	$ 245		245
Restricted Stock Award - Board of Directors, shares	4,000
Cash Dividends on Common Stock		(13,418)	(13,418)
Cash Dividends on Preferred Stock		(90)	(90)
Common Stock Expenses		(37)	(37)
Balance at Sep. 30, 2020	$ 216,866	125,240	342,106
Balance, shares at Sep. 30, 2020	17,469,000
Balance at Jun. 30, 2020	$ 216,365	117,008	333,373
Balance, shares at Jun. 30, 2020	17,464,000
Net Income		12,737	12,737
Dividend Reinvestment & Common Stock Purchase Plan	$ 313		313
Dividend Reinvestment & Common Stock Purchase Plan, shares	5,000
Restricted Stock Award, Net - Employees	$ 188		188
Cash Dividends on Common Stock		(4,475)	(4,475)
Cash Dividends on Preferred Stock		(30)	(30)
Balance at Sep. 30, 2020	$ 216,866	$ 125,240	$ 342,106
Balance, shares at Sep. 30, 2020	17,469,000