Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Sep. 30, 2019	1,805,053	(424,307)
Balance at Sep. 30, 2019	$ 18,000	$ (4,000)	$ 1,755,000	$ 135,931,000	$ 137,700,000
Net income (loss)	$ 0	$ 0	0	14,210,000	14,210,000
Balance (in shares) at Dec. 31, 2019	1,805,053	(424,307)
Balance at Dec. 31, 2019	$ 18,000	$ (4,000)	1,755,000	150,141,000	151,910,000
Balance (in shares) at Sep. 30, 2019	1,805,053	(424,307)
Balance at Sep. 30, 2019	$ 18,000	$ (4,000)	1,755,000	135,931,000	137,700,000
Net income (loss)					(27,842,000)
Balance (in shares) at Jun. 30, 2020	1,805,053	(424,307)
Balance at Jun. 30, 2020	$ 18,000	$ (4,000)	1,755,000	108,089,000	109,858,000
Balance (in shares) at Dec. 31, 2019	1,805,053	(424,307)
Balance at Dec. 31, 2019	$ 18,000	$ (4,000)	1,755,000	150,141,000	151,910,000
Net income (loss)	$ 0	$ 0	0	(56,326,000)	(56,326,000)
Balance (in shares) at Mar. 31, 2020	1,805,053	(424,307)
Balance at Mar. 31, 2020	$ 18,000	$ (4,000)	1,755,000	93,815,000	95,584,000
Net income (loss)	$ 0	$ 0	0	14,274,000	14,274,000
Balance (in shares) at Jun. 30, 2020	1,805,053	(424,307)
Balance at Jun. 30, 2020	$ 18,000	$ (4,000)	1,755,000	108,089,000	109,858,000
Balance (in shares) at Sep. 30, 2020	1,805,053	(424,307)
Balance at Sep. 30, 2020	$ 18,000	$ (4,000)	1,755,000	139,972,000	141,741,000
Net income (loss)	$ 0	$ 0	0	59,270,000	59,270,000
Balance (in shares) at Dec. 31, 2020	1,805,053	(424,307)
Balance at Dec. 31, 2020	$ 18,000	$ (4,000)	1,755,000	199,242,000	201,011,000
Balance (in shares) at Sep. 30, 2020	1,805,053	(424,307)
Balance at Sep. 30, 2020	$ 18,000	$ (4,000)	1,755,000	139,972,000	141,741,000
Net income (loss)					114,319,000
Balance (in shares) at Jun. 30, 2021	1,805,053	(424,307)
Balance at Jun. 30, 2021	$ 18,000	$ (4,000)	1,755,000	254,291,000	256,060,000
Balance (in shares) at Dec. 31, 2020	1,805,053	(424,307)
Balance at Dec. 31, 2020	$ 18,000	$ (4,000)	1,755,000	199,242,000	201,011,000
Net income (loss)	$ 0	$ 0	0	12,476,000	12,476,000
Balance (in shares) at Mar. 31, 2021	1,805,053	(424,307)
Balance at Mar. 31, 2021	$ 18,000	$ (4,000)	1,755,000	211,718,000	213,487,000
Net income (loss)	$ 0	$ 0	0	42,573,000	42,573,000
Balance (in shares) at Jun. 30, 2021	1,805,053	(424,307)
Balance at Jun. 30, 2021	$ 18,000	$ (4,000)	$ 1,755,000	$ 254,291,000	$ 256,060,000