Statements of Income (Unaudited) - USD ($)	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Revenue
Revenue	$ 7,107,906	$ 7,607,666
Cost of sales	1,396,005	1,798,366
Gross profit	5,711,901	5,809,300
Expenses
Research and development	989,026	905,725
Selling, general, and administrative	328,761	399,361
Total expenses	1,317,787	1,305,086
Income from operations	4,394,114	4,504,214
Interest income	424,770	361,778
Income before taxes	4,818,884	4,865,992
Provision for income taxes	873,835	1,568,377
Net income	$ 3,945,049	$ 3,297,615
Net income per share – basic (in dollars per share)	$ 0.81	$ 0.68
Net income per share – diluted (in dollars per share)	0.81	0.68
Cash dividends declared per common share (in dollars per share)	$ 1	$ 1
Weighted average shares outstanding
Basic (in shares)	4,842,010	4,841,010
Diluted (in shares)	4,850,479	4,846,251
Product [Member]
Revenue
Revenue	$ 6,870,646	$ 6,882,673
Contract Research and Development [Member]
Revenue
Revenue	$ 237,260	$ 724,993