Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	$ 4,882	$ 5,879	$ 14,308	$ 13,441
Stock-based compensation expensed from (capitalized to) inventory	25	(3)	5	11
Total stock-based compensation expense	4,857	5,882	14,303	13,430
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	97	118	226	353
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	2,992	1,545	9,039	4,867
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	1,793	4,216	5,043	8,221
Stock Options [Member]
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation expense by type of grant	454	648	1,160	1,987
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	$ 4,428	$ 5,231	$ 13,148	$ 11,454