Note L - Stockholders' Equity - Schedule of Stockholders' Equity (Details) - USD ($)	3 Months Ended				6 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Balance at March 31, 2021	$ 62,942,275	$ 65,339,976	$ 65,974,090	$ 66,865,367	$ 65,339,976	$ 66,865,367
Net earnings	13,177,614	11,311,797	(250,005)	(858,862)	24,489,411	(1,108,867)
Other comprehensive loss	4,227,185	(13,693,337)
Paid in capital – restricted stock awards	126,037	121,704	110,813	110,814
Cash dividends	(138,110)	(137,865)	(143,181)	(143,229)
Net earnings (loss)	13,177,614	11,311,797	(250,005)	(858,862)	24,489,411	(1,108,867)
Issuance of restricted stock	0			0
Balance at September 30, 2021	80,335,001	62,942,275	65,281,496	65,974,090	80,335,001	65,281,496
Repurchase of shares			(410,221)
Common Stock [Member]
Balance at March 31, 2021	8,334,785	8,334,785	8,306,160	8,295,160	8,334,785	8,295,160
Issuance of restricted stock	6,000			11,000
Balance at September 30, 2021	8,340,785	8,334,785	8,306,160	8,306,160	8,340,785	8,306,160
AOCI Attributable to Parent [Member]
Balance at March 31, 2021	(24,881,178)	(11,187,841)			(11,187,841)
Other comprehensive loss	4,227,185	(13,693,337)
Balance at September 30, 2021	(20,653,993)	(24,881,178)			(20,653,993)
Additional Paid-in Capital [Member]
Balance at March 31, 2021	30,125,166	30,003,462	29,665,230	29,565,416	30,003,462	29,565,416
Paid in capital – restricted stock awards	126,037	121,704	110,813	110,814
Balance at September 30, 2021	30,245,203	30,125,166	29,776,043	29,665,230	30,245,203	29,776,043
Treasury Stock [Member]
Balance at March 31, 2021	(7,203,342)	(7,203,342)	(5,525,964)	(5,525,964)	(7,203,342)	(5,525,964)
Cash dividends			0
Balance at September 30, 2021	(7,203,342)	(7,203,342)	(5,936,185)	(5,525,964)	(7,203,342)	(5,936,185)
Repurchase of shares			(410,221)
Retained Earnings [Member]
Balance at March 31, 2021	56,566,844	45,392,912	33,528,664	34,530,755	45,392,912	34,530,755
Net earnings	13,177,614	11,311,797	(250,005)	(858,862)
Cash dividends	(138,110)	(137,865)	(143,181)	(143,229)
Net earnings (loss)	13,177,614	11,311,797	(250,005)	(858,862)
Balance at September 30, 2021	$ 69,606,348	$ 56,566,844	$ 33,135,478	$ 33,528,664	$ 69,606,348	$ 33,135,478