STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($)	Common Stock	Additional Paid-in Capital	AOCI Including Portion Attributable to Noncontrolling Interest	Retained Earnings	Total
Equity Balance, Starting at Mar. 31, 2021	$ 48,332	$ 19,338,127	$ 1,101,119	$ 50,404,364	$ 70,891,942
Shares Outstanding, Starting at Mar. 31, 2021	4,833,232
Unrealized gain (loss) from marketable securities, net of tax			(90,165)		(90,165)
Net income				3,579,566	3,579,566
Total comprehensive income					3,489,401
Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture		7,238			7,238
Cash dividends declared ($1.00 per share of common stock)				(4,833,232)	(4,833,232)
Shares Outstanding, Ending at Jun. 30, 2021	4,833,232
Equity Balance, Ending at Jun. 30, 2021	$ 48,332	19,345,365	1,010,954	49,150,698	69,555,349
Equity Balance, Starting at Mar. 31, 2021	$ 48,332	19,338,127	1,101,119	50,404,364	70,891,942
Shares Outstanding, Starting at Mar. 31, 2021	4,833,232
Unrealized gain (loss) from marketable securities, net of tax					(667,361)
Net income					10,691,481
Total comprehensive income					10,024,120
Shares Outstanding, Ending at Dec. 31, 2021	4,833,714
Equity Balance, Ending at Dec. 31, 2021	$ 48,337	19,411,158	433,759	46,596,148	66,489,402
Equity Balance, Starting at Jun. 30, 2021	$ 48,332	19,345,365	1,010,954	49,150,698	69,555,349
Shares Outstanding, Starting at Jun. 30, 2021	4,833,232
Unrealized gain (loss) from marketable securities, net of tax			(197,034)		(197,034)
Net income				3,646,507	3,646,507
Total comprehensive income					3,449,473
Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture		56,999			56,999
Cash dividends declared ($1.00 per share of common stock)				(4,833,232)	(4,833,232)
Shares Outstanding, Ending at Sep. 30, 2021	4,833,232
Equity Balance, Ending at Sep. 30, 2021	$ 48,332	19,402,364	813,920	47,963,973	68,228,589
Unrealized gain (loss) from marketable securities, net of tax			(380,161)		(380,161)
Net income				3,465,407	3,465,407
Total comprehensive income					3,085,246
Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture		8,799			8,799
Cash dividends declared ($1.00 per share of common stock)				(4,833,232)	(4,833,232)
Stock Issued During Period, Value, Stock Options Exercised	$ 5	(5)			0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period	482
Shares Outstanding, Ending at Dec. 31, 2021	4,833,714
Equity Balance, Ending at Dec. 31, 2021	$ 48,337	19,411,158	433,759	46,596,148	66,489,402
Equity Balance, Starting at Mar. 31, 2022	$ 48,308	19,256,485	(318,120)	45,578,456	64,565,129
Shares Outstanding, Starting at Mar. 31, 2022	4,830,826
Unrealized gain (loss) from marketable securities, net of tax			(338,553)		(338,553)
Net income				4,140,116	4,140,116
Total comprehensive income					3,801,563
Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture		7,134			7,134
Cash dividends declared ($1.00 per share of common stock)				(4,830,826)	(4,830,826)
Shares Outstanding, Ending at Jun. 30, 2022	4,830,826
Equity Balance, Ending at Jun. 30, 2022	$ 48,308	19,263,619	(656,673)	44,887,746	63,543,000
Equity Balance, Starting at Mar. 31, 2022	$ 48,308	19,256,485	(318,120)	45,578,456	64,565,129
Shares Outstanding, Starting at Mar. 31, 2022	4,830,826
Unrealized gain (loss) from marketable securities, net of tax					(1,133,242)
Net income					14,461,814
Total comprehensive income					13,328,572
Shares Outstanding, Ending at Dec. 31, 2022	4,830,826
Equity Balance, Ending at Dec. 31, 2022	$ 48,308	19,310,703	(1,451,362)	45,547,791	63,455,440
Equity Balance, Starting at Jun. 30, 2022	$ 48,308	19,263,619	(656,673)	44,887,746	63,543,000
Shares Outstanding, Starting at Jun. 30, 2022	4,830,826
Unrealized gain (loss) from marketable securities, net of tax			(1,127,362)		(1,127,362)
Net income				6,090,373	6,090,373
Total comprehensive income					4,963,011
Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture		39,951			39,951
Cash dividends declared ($1.00 per share of common stock)				(4,830,826)	(4,830,826)
Shares Outstanding, Ending at Sep. 30, 2022	4,830,826
Equity Balance, Ending at Sep. 30, 2022	$ 48,308	19,303,570	(1,784,035)	46,147,293	63,715,136
Unrealized gain (loss) from marketable securities, net of tax			332,673		332,673
Net income				4,231,324	4,231,324
Total comprehensive income					4,563,997
Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture		7,133			7,133
Cash dividends declared ($1.00 per share of common stock)				(4,830,826)	(4,830,826)
Shares Outstanding, Ending at Dec. 31, 2022	4,830,826
Equity Balance, Ending at Dec. 31, 2022	$ 48,308	$ 19,310,703	$ (1,451,362)	$ 45,547,791	$ 63,455,440