Statements of Income (USD $)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Revenue
Product sales	$ 29,894,045	$ 25,512,028	$ 24,434,823
Contract research and development	690,043	422,879	2,598,596
Total revenue	30,584,088	25,934,907	27,033,419
Cost of sales	6,019,868	5,720,277	7,025,181
Gross profit	24,564,220	20,214,630	20,008,238
Expenses
Selling, general , and administrative	2,312,076	2,235,475	2,240,563
Research and development	3,000,193	3,585,339	2,570,821
Total expenses	5,312,269	5,820,814	4,811,384
Income from operations	19,251,951	14,393,816	15,196,854
Interest income	2,187,723	2,122,133	2,359,603
Income before taxes	21,439,674	16,515,949	17,556,457
Provision for income taxes	7,071,320	5,380,074	5,727,619
Net income	$ 14,368,354	$ 11,135,875	$ 11,828,838
Net income per share - basic	$ 2.96	$ 2.30	$ 2.44
Net income per share - diluted	$ 2.95	$ 2.29	$ 2.43
Cash dividends declared per common share	$ 2.06	$ 0	$ 0
Weighted average shares outstanding
Basic	4,855,504	4,851,460	4,839,810
Diluted	4,871,935	4,867,691	4,863,546