Statements of Income (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Revenue
Revenue	$ 6,533,362	$ 6,464,596	$ 15,503,409	$ 19,261,237
Cost of sales	1,075,048	1,263,806	2,852,757	3,701,941
Gross profit	5,458,314	5,200,790	12,650,652	15,559,296
Expenses
Research and development	702,216	771,468	2,399,164	2,671,131
Selling, general, and administrative	311,356	327,989	1,024,549	1,026,448
Total expenses	1,013,572	1,099,457	3,423,713	3,697,579
Income from operations	4,444,742	4,101,333	9,226,939	11,861,717
Interest income	365,498	443,478	1,166,102	1,358,826
Income before taxes	4,810,240	4,544,811	10,393,041	13,220,543
Provision for income taxes	884,531	814,147	1,833,127	2,060,398
Net income	$ 3,925,709	$ 3,730,664	$ 8,559,914	$ 11,160,145
Net income per share – basic (in dollars per share)	$ 0.81	$ 0.77	$ 1.77	$ 2.30
Net income per share – diluted (in dollars per share)	0.81	0.77	1.77	2.30
Cash dividends declared per common share (in dollars per share)	$ 1	$ 1	$ 3	$ 3
Weighted average shares outstanding
Basic (in shares)	4,833,232	4,846,010	4,834,324	4,846,010
Diluted (in shares)	4,833,261	4,847,436	4,834,411	4,848,506
Product [Member]
Revenue
Revenue	$ 6,332,349	$ 6,160,967	$ 14,850,157	$ 18,434,039
Contract Research and Development [Member]
Revenue
Revenue	$ 201,013	$ 303,629	$ 653,252	$ 827,198