Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	$ 4,228	$ 3,836	$ 9,426	$ 7,562
Stock-based compensation expensed from (capitalized to) inventory	(2)	2	(20)	14
Total stock-based compensation expense	4,230	3,834	9,446	7,548
Cost of Revenues [Member]
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	100	127	129	235
Research and Development Expense [Member]
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	2,776	1,524	6,047	3,322
Selling General and Administrative [Member]
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	1,352	2,185	3,250	4,005
Stock Options [Member]
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	292	737	706	1,339
Restricted Stock Units [Member]
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	$ 3,936	$ 3,099	$ 8,720	$ 6,223