Statements of Shareholders' Equity (Unaudited) - USD ($)	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Mar. 31, 2019		4,846,010
Balance at Mar. 31, 2019		$ 48,460	$ 19,910,558	$ (82,725)	$ 62,903,918	$ 82,780,211
Unrealized gain on marketable securities, net of tax				570,063		570,063
Net income					3,607,419	3,607,419
Total comprehensive income						4,177,482
Cash dividends declared					(4,846,010)	(4,846,010)
Balance (in shares) at Jun. 30, 2019	4,846,010
Balance at Jun. 30, 2019		$ 48,460	19,910,558	487,338	61,665,327	82,111,683
Balance (in shares) at Mar. 31, 2019		4,846,010
Balance at Mar. 31, 2019		$ 48,460	19,910,558	(82,725)	62,903,918	82,780,211
Unrealized gain on marketable securities, net of tax						1,242,662
Net income						2,411,865
Total comprehensive income						3,654,527
Balance (in shares) at Mar. 31, 2020		4,835,038
Balance at Mar. 31, 2020		$ 48,350	19,383,956	516,523	58,046,520	77,995,349	[1]
Unrealized gain on marketable securities, net of tax				1,242,662		1,242,662
Net income					2,411,865	2,411,865
Total comprehensive income						3,654,527
Stock-based compensation			2,707			2,707
Cash dividends declared					(4,835,038)	(4,835,038)
Balance (in shares) at Jun. 30, 2020	4,835,038
Balance at Jun. 30, 2020		$ 48,350	$ 19,386,663	$ 1,759,185	$ 55,623,347	$ 76,817,545

[1] The March 31, 2020 Balance Sheet is derived from the audited financial statements contained in our Annual Report on Form 10-K for the fiscal year ended March 31, 2020.