Share-Based Compensation - Expense (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	616,000	550,500
Total share-based compensation expense	$ 1,234,000	$ 1,900,000	$ 3,868,000	$ 4,877,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		5,000
Cost of Sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense	189,000	217,000	374,000	433,000
Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense	666,000	1,017,000	2,760,000	3,278,000
Research and Development Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense	379,000	666,000	734,000	1,166,000
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 8,600,000		$ 8,600,000