Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of Stock-Based Compensation Expense
Stock based compensation	$ 3,836	$ 7,632	$ 7,562	$ 15,240
Stock-based compensation expensed from inventory	(2)	2	(14)	83
Total stock-based compensation expense	3,834	7,634	7,548	15,323
Cost of Revenues [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	127	175	235	355
Research and Development [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	1,524	3,714	3,322	7,919
Selling, General and Administrative [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	$ 2,185	$ 3,743	$ 4,005	$ 6,966