Consolidated Statements of Stockholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2019	$ 21,640,000	$ 206,000	$ 5,817,000	$ (5,000)	$ 15,649,000	$ (27,000)
Net Income (Loss)	(942,000)	0	0	0	(942,000)	0
Dividends, Common Stock	(656,000)	0	0	0	(656,000)	0
Other Comprehensive Loss	(3,000)	0	0	(3,000)	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(6,000)	0	(7,000)	0	0	1,000
Restricted Stock and Restricted Stock Units, Net	0	0	(7,000)	0	0	7,000
Stock-Based Compensation Expenses	113,000	0	113,000	0	0	0
Treasury Stock Issued as Compensation	2,000	0	0	0	0	2,000
Balance at Sep. 30, 2020	20,148,000	206,000	5,916,000	(8,000)	14,051,000	(17,000)
Balance at Jun. 30, 2020	20,388,000	206,000	5,886,000	(5,000)	14,312,000	(11,000)
Net Income (Loss)	(42,000)	0	0	0	(42,000)	0
Dividends, Common Stock	(219,000)	0	0	0	(219,000)	0
Other Comprehensive Loss	(3,000)	0	0	(3,000)	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(10,000)	0	0	0	0	(10,000)
Restricted Stock and Restricted Stock Units, Net	0	0	(3,000)	0	0	3,000
Stock-Based Compensation Expenses	33,000	0	33,000	0	0	0
Treasury Stock Issued as Compensation	1,000	0	0	0	0	1,000
Balance at Sep. 30, 2020	20,148,000	206,000	5,916,000	(8,000)	14,051,000	(17,000)
Balance at Dec. 31, 2020	20,302,000	206,000	5,945,000	(12,000)	14,170,000	(7,000)
Net Income (Loss)	2,679,000	0	0	0	2,679,000	0
Dividends, Common Stock	(1,307,000)	0	0	0	(1,307,000)	0
Other Comprehensive Loss	(1,000)	0	0	(1,000)	0	0
Common Stock Issued Under Stock Plans	9,000	0	9,000	0	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(34,000)	0	(7,000)	0	0	(27,000)
Restricted Stock and Restricted Stock Units, Net	0	0	(6,000)	0	0	6,000
Stock-Based Compensation Expenses	117,000	0	117,000	0	0	0
Treasury Stock Issued as Compensation	0	0	0	0	0	0
Balance at Sep. 30, 2021	21,765,000	206,000	6,058,000	(13,000)	15,542,000	(28,000)
Balance at Jun. 30, 2021	20,881,000	206,000	6,017,000	(15,000)	14,689,000	(16,000)
Net Income (Loss)	1,095,000	0	0	0	1,095,000	0
Dividends, Common Stock	(242,000)	0	0	0	(242,000)	0
Other Comprehensive Loss	2,000	0	0	2,000	0	0
Common Stock Issued Under Stock Plans	0	0	0	0	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(22,000)	0	(5,000)	0	0	(17,000)
Restricted Stock and Restricted Stock Units, Net	0	0	(5,000)	0	0	5,000
Stock-Based Compensation Expenses	51,000	0	51,000	0	0	0
Treasury Stock Issued as Compensation	0	0	0	0	0	0
Balance at Sep. 30, 2021	$ 21,765,000	$ 206,000	$ 6,058,000	$ (13,000)	$ 15,542,000	$ (28,000)