Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Revenue:
Product revenue	$ 445,195	$ 329,520	$ 229,950
Funded research and development	109	23	361
Total Revenue	445,304	329,543	230,311
Costs and expenses:
Cost of product revenue	70,627	50,419	39,945
Research and development	66,386	49,759	35,973
Selling, general and administrative	218,153	164,261	125,727
Costs and Expenses, Total	355,166	264,439	201,645
Income from operations	90,138	65,104	28,666
Other income:
Investment income, net	1,554	395	196
Other (expense) income, net	(349)	339	(97)
Nonoperating Income (Expense), Total	1,205	734	99
Income before income taxes	91,343	65,838	28,765
Income tax provision (benefit)	39,227	27,691	(84,923)
Net income	$ 52,116	$ 38,147	$ 113,688
Basic net income per share	$ 1.21	$ 0.90	$ 2.80
Basic weighted average shares outstanding	43,238	42,204	40,632
Diluted net income per share	$ 1.17	$ 0.85	$ 2.65
Diluted weighted average shares outstanding	44,658	44,895	42,858