Stock-Based Compensation - Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	$ 1,347,000	$ 1,177,000	$ 1,521,000	$ 2,061,000
Cost of Sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	129,000	69,000	114,000	128,000
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	236,000	488,000	109,000	790,000
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Stock-based compensation expense	$ 982,000	$ 620,000	$ 1,298,000	$ 1,143,000