Annual report pursuant to Section 13 and 15(d)

Property And Equipment (Schedule Of Property And Equipment) (Details)

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Property And Equipment (Schedule Of Property And Equipment) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 29, 2018
Dec. 30, 2017
Dec. 31, 2016
Property, Plant and Equipment [Line Items]      
Property and equipment, gross $ 178,087 $ 177,355  
Less accumulated depreciation and amortization 95,561 86,202  
Property and equipment, net 82,526 91,153  
Property and equipment, net 92,025 102,847  
Depreciation $ 15,222 14,480 $ 11,878
Buildings [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 39 years 6 months    
Property and equipment, gross $ 71,326 73,344  
Laboratory And Production Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, gross 31,969 31,063  
Computer Equipment And Software [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, gross 51,410 50,124  
Furniture And Fixtures [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, gross 6,524 6,453  
Automobiles [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, gross 682 562  
Leasehold Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, gross $ 13,102 12,740  
Land Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 15 years    
Property and equipment, gross $ 3,074 3,069  
Land [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, net 7,052 7,521  
Deposits And Projects In Process [Member]      
Property, Plant and Equipment [Line Items]      
Property and equipment, net $ 2,447 $ 4,173  
Minimum [Member] | Laboratory And Production Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 5 years    
Minimum [Member] | Computer Equipment And Software [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 3 years    
Minimum [Member] | Furniture And Fixtures [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 3 years    
Minimum [Member] | Automobiles [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 3 years    
Minimum [Member] | Leasehold Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 3 years    
Maximum [Member] | Laboratory And Production Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 7 years    
Maximum [Member] | Computer Equipment And Software [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 5 years    
Maximum [Member] | Furniture And Fixtures [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 5 years    
Maximum [Member] | Automobiles [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 5 years    
Maximum [Member] | Leasehold Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Useful life 5 years