Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary of Stock-Based Compensation Expense
Stock based compensation	$ 7,632	$ 3,095	$ 15,240	$ 7,270
Stock-based compensation expensed from inventory	2	29	83	32
Total stock-based compensation expense	7,634	3,124	15,323	7,302
Cost of Revenues [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	175	69	355	177
Research and Development [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	3,714	1,726	7,919	4,114
Selling, General and Administrative [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	$ 3,743	$ 1,300	$ 6,966	$ 2,979