Statements Of Income (USD $)
 3 Months Ended 9 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Revenue        
Product sales $ 6,448,407 $ 5,762,925 $ 19,654,162 $ 18,025,002
Contract research and development 25,290 762,296 297,648 1,785,920
Total revenue 6,473,697 6,525,221 19,951,810 19,810,922
Cost of sales 1,449,396 1,738,618 4,331,297 5,147,884
Gross profit 5,024,301 4,786,603 15,620,513 14,663,038
Expenses        
Selling, general , and administrative 543,698 570,741 1,756,578 1,714,545
Research and development 905,246 501,325 2,744,620 1,801,609
Total expenses 1,448,944 1,072,066 4,501,198 3,516,154
Income from operations 3,575,357 3,714,537 11,119,315 11,146,884
Interest income 530,383 600,395 1,577,524 1,784,963
Income before taxes 4,105,740 4,314,932 12,696,839 12,931,847
Provision for income taxes 1,328,566 1,415,590 4,123,189 4,211,964
Net income $ 2,777,174 $ 2,899,342 $ 8,573,650 $ 8,719,883
Net income per share - basic $ 0.57 $ 0.60 $ 1.77 $ 1.80
Net income per share - diluted $ 0.57 $ 0.60 $ 1.76 $ 1.80
Weighted average shares outstanding        
Basic 4,842,565 4,847,619 4,852,356 4,832,630
Diluted 4,859,601 4,872,019 4,868,040 4,856,851