Contractual Obligations and Commercial Contingencies (Details) (USD $)	3 Months Ended
	Jun. 29, 2012	Mar. 30, 2012	Jun. 24, 2011
Debt Instrument [Line Items]
Outstanding amount of debt	$ 10,500,000	10,500,000
Outstanding amount of debt	22,500,000	23,704,000
License and Development Agreement [Abstract]
Additional license fee to be paid	5,000,000
Total number of installments	4
Number of installments paid	2
Number of installments remaining	2
Contingencies [Abstract]
Contractual obligations and contingencies	45,100,000	46,700,000
Convertible senior notes [Member]
Debt Instrument [Line Items]
Interest rate of long-term debt (in hundredths)	3.75%	3.75%	3.75%
Face value of debt	85,000,000
Date of maturity	Dec. 15, 2014
Outstanding amount of debt			10,500,000
Common Stock Issued Per Specified Amount Of Outstanding Debt (in shares)	73.3689
Amount of debt (tranche) specified for conversion into common stock	1,000
Conversion price of debt instrument (in dollars per share)	$ 13.63
Purchase price of note as a percentage of principal amount (in hundredths)	100.00%
Redeemable convertible subordinated debentures [Member]
Debt Instrument [Line Items]
Interest rate of long-term debt (in hundredths)	7.25%	7.25%	7.25%
Face value of debt	75,000,000
Date of maturity	May 15, 2014
Outstanding amount of debt			23,700,000
Conversion price of debt instrument (in dollars per share)	$ 31.50
Number of annual sinking fund payments	14
Percentage of aggregate principal amount of debt (in hundredths)	5.00%
Annual payments to sinking fund	3,800,000
Sinking fund requirement	$ 1,200,000