Stock-Based Compensation Recognized (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 1,648	$ 1,936	$ 8,367	$ 6,899
Cost of product revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	130	83	476	330
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	527	333	1,813	1,331
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 991	$ 1,520	$ 6,078	$ 5,238