CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS EQUITY - USD ($)	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Total
Balance at Jun. 30, 2019	$ 212,000	$ 17,103,000	$ (17,067,000)	$ 70,924,000	$ 71,172,000
Balance (in shares) at Jun. 30, 2019	21,227,094		(2,749,310)
Stock-based compensation expense		17,000			17,000
Net income				3,233,000	3,233,000
Balance at Sep. 30, 2019	$ 212,000	17,120,000	$ (17,067,000)	74,157,000	74,422,000
Balance (in shares) at Sep. 30, 2019	21,227,094		(2,749,310)
Balance at Jun. 30, 2019	$ 212,000	17,103,000	$ (17,067,000)	70,924,000	71,172,000
Balance (in shares) at Jun. 30, 2019	21,227,094		(2,749,310)
Balance at Dec. 31, 2019	$ 212,000	17,428,000	$ (17,067,000)	77,729,000	78,302,000
Balance (in shares) at Dec. 31, 2019	21,227,094		(2,749,310)
Balance at Jun. 30, 2019	$ 212,000	17,103,000	$ (17,067,000)	70,924,000	71,172,000
Balance (in shares) at Jun. 30, 2019	21,227,094		(2,749,310)
Net income					10,420,000
Repurchase of treasury shares (in shares)			137,303
Balance at Mar. 31, 2020	$ 212,000	17,671,000	$ (19,417,000)	81,344,000	79,810,000
Balance (in shares) at Mar. 31, 2020	21,239,692		(2,886,613)
Balance at Jun. 30, 2019	$ 212,000	17,103,000	$ (17,067,000)	70,924,000	71,172,000
Balance (in shares) at Jun. 30, 2019	21,227,094		(2,749,310)
Balance at Jun. 30, 2020	$ 212,000	17,766,000	$ (19,521,000)	79,444,000	77,901,000
Balance (in shares) at Jun. 30, 2020	21,241,066		(2,893,715)
Balance at Sep. 30, 2019	$ 212,000	17,120,000	$ (17,067,000)	74,157,000	74,422,000
Balance (in shares) at Sep. 30, 2019	21,227,094		(2,749,310)
Stock-based compensation expense		308,000			308,000
Net income				3,572,000	3,572,000
Balance at Dec. 31, 2019	$ 212,000	17,428,000	$ (17,067,000)	77,729,000	78,302,000
Balance (in shares) at Dec. 31, 2019	21,227,094		(2,749,310)
Stock-based compensation expense		172,000			172,000
Stock Options exercised	$ 12,598	71,000			71,000
Net income				3,615,000	3,615,000
Repurchase of treasury shares			$ (2,350,000)		(2,320,000)
Balance at Mar. 31, 2020	$ 212,000	17,671,000	$ (19,417,000)	81,344,000	79,810,000
Balance (in shares) at Mar. 31, 2020	21,239,692		(2,886,613)
Balance at Jun. 30, 2020	$ 212,000	17,766,000	$ (19,521,000)	79,444,000	77,901,000
Balance (in shares) at Jun. 30, 2020	21,241,066		(2,893,715)
Stock-based compensation expense		104,000			104,000
Net income				2,319,000	2,319,000
Balance at Sep. 30, 2020	$ 212,000	17,870,000	$ (19,521,000)	81,763,000	80,324,000
Balance (in shares) at Sep. 30, 2020	21,241,066		(2,893,715)
Balance at Jun. 30, 2020	$ 212,000	17,766,000	$ (19,521,000)	79,444,000	77,901,000
Balance (in shares) at Jun. 30, 2020	21,241,066		(2,893,715)
Balance at Dec. 31, 2020	$ 212,000	17,954,000	$ (19,521,000)	84,960,000	83,605,000
Balance (in shares) at Dec. 31, 2020	21,241,066		(2,893,715)
Balance at Jun. 30, 2020	$ 212,000	17,766,000	$ (19,521,000)	79,444,000	77,901,000
Balance (in shares) at Jun. 30, 2020	21,241,066		(2,893,715)
Net income					9,876,000
Balance at Mar. 31, 2021	$ 212,000	18,038,000	$ (19,521,000)	89,320,000	88,049,000
Balance (in shares) at Mar. 31, 2021	21,243,926		(2,893,715)
Balance at Sep. 30, 2020	$ 212,000	17,870,000	$ (19,521,000)	81,763,000	80,324,000
Balance (in shares) at Sep. 30, 2020	21,241,066		(2,893,715)
Stock-based compensation expense		84,000			84,000
Net income				3,197,000	3,197,000
Balance at Dec. 31, 2020	$ 212,000	17,954,000	$ (19,521,000)	84,960,000	83,605,000
Balance (in shares) at Dec. 31, 2020	21,241,066		(2,893,715)
Stock-based compensation expense		84,000			84,000
Stock Options exercised (in shares)	2,860
Net income				4,360,000	4,360,000
Balance at Mar. 31, 2021	$ 212,000	$ 18,038,000	$ (19,521,000)	$ 89,320,000	$ 88,049,000
Balance (in shares) at Mar. 31, 2021	21,243,926		(2,893,715)