Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Summary of Stock-Based Compensation Expense
Stock based compensation	$ 3,726	$ 7,608
Stock-based compensation expensed from inventory	(12)	81
Total stock-based compensation expense	3,714	7,689
Cost of Revenues [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	108	180
Research and Development [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	1,798	4,205
Selling, General and Administrative [Member]
Summary of Stock-Based Compensation Expense
Stock based compensation	$ 1,820	$ 3,223