Share-Based Compensation - Expense (Details) (USD $)	3 Months Ended
	Jun. 29, 2013	Jun. 30, 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	611,500	189,500
Total share-based compensation expense	$ 2,634,000	$ 2,977,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2 years 3 months 18 days
Cost of Sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense	185,000	216,000
Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense	2,094,000	2,261,000
Research and Development Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense	355,000	500,000
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	$ 9,900,000
Nineteen Ninety Employee Stock Purchase Plan [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	15.00%
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85.00%
Employee Purchase Plan Length Of Offering Period	24 months