Statements of Income - USD ($)	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Revenue
Product sales	$ 24,410,391	$ 29,894,045	$ 25,512,028
Contract research and development	3,306,887	690,043	422,879
Total revenue	27,717,278	30,584,088	25,934,907
Cost of sales	6,616,852	6,019,868	5,720,277
Gross profit	21,100,426	24,564,220	20,214,630
Expenses
Selling, general, and administrative	1,752,962	2,312,076	2,235,475
Research and development	3,061,184	3,000,193	3,585,339
Total expenses	4,814,146	5,312,269	5,820,814
Income from operations	16,286,280	19,251,951	14,393,816
Interest income	1,890,817	2,187,723	2,122,133
Income before taxes	18,177,097	21,439,674	16,515,949
Provision for income taxes	5,884,782	7,071,320	5,380,074
Net income	$ 12,292,315	$ 14,368,354	$ 11,135,875
Net income per share – basic (in dollars per share)	$ 2.53	$ 2.96	$ 2.30
Net income per share – diluted (in dollars per share)	2.53	2.95	$ 2.29
Cash dividends declared per common share (in dollars per share)	$ 4	$ 2.06
Weighted average shares outstanding
Basic (in shares)	4,850,209	4,855,504	4,851,460
Diluted (in shares)	4,852,602	4,871,935	4,867,691