Restructuring and Divestiture Charges - Additional Information (Detail) (USD $)
 3 Months Ended 6 Months Ended 12 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended
Sep. 27, 2014
Mar. 28, 2015
Mar. 28, 2015
Sep. 27, 2014
Mar. 29, 2014
Mar. 29, 2014
Dec. 28, 2013
Dec. 27, 2014
Restructuring Cost and Reserve [Line Items]                
Gain (Loss) on Disposition of Business $ 5,300,000              
Restructuring | Fiscal 2015 Charges                
Restructuring Cost and Reserve [Line Items]                
Severance charges   500,000 3,000,000          
Share Based Compensation Expense Included Other Restructuring Costs     100,000          
Workforce reductions     9,200,000          
Facility closure costs     800,000          
Restructuring | Fiscal 2014 Charges                
Restructuring Cost and Reserve [Line Items]                
Workforce reductions       42,200,000        
Facility closure costs       600,000        
Non-cash impairment charge       3,100,000        
Consolidation of Diagnostics Operations | Molecular Diagnostics Operations                
Restructuring Cost and Reserve [Line Items]                
Severance charges       3,000,000 900,000 1,700,000    
Severance and benefits and facility closure costs     500,000          
Consolidation of Diagnostics Operations | Restructuring | Fiscal 2015 Charges                
Restructuring Cost and Reserve [Line Items]                
Workforce reductions     100,000          
Facility closure costs     400,000          
Consolidation of Diagnostics Operations | Restructuring | Fiscal 2014 Charges                
Restructuring Cost and Reserve [Line Items]                
Workforce reductions       2,900,000        
Facility closure costs       0        
Non-cash impairment charge       0        
Fiscal 2014 Actions                
Restructuring Cost and Reserve [Line Items]                
Severance charges       16,600,000 3,000,000   6,300,000  
Compensation charges       1,800,000     400,000  
Fiscal 2014 Actions | Jack Cumming                
Restructuring Cost and Reserve [Line Items]                
Severance charges         200,000   6,600,000  
Compensation charges             4,400,000  
Fiscal 2014 Actions | Restructuring | Fiscal 2015 Charges                
Restructuring Cost and Reserve [Line Items]                
Workforce reductions   1,400,000 5,900,000         4,500,000
Facility closure costs     200,000         200,000
Fiscal 2014 Actions | Restructuring | Fiscal 2014 Charges                
Restructuring Cost and Reserve [Line Items]                
Workforce reductions       29,500,000        
Facility closure costs       0        
Non-cash impairment charge       0        
Other Operating Cost Reductions                
Restructuring Cost and Reserve [Line Items]                
Severance charges       8,700,000 7,300,000   0  
Number of employees affected for severance benefits             95  
Estimated aggregate severance charges   9,300,000 9,300,000          
Other Operating Cost Reductions | Restructuring | Fiscal 2015 Charges                
Restructuring Cost and Reserve [Line Items]                
Severance and benefits and facility closure costs     400,000          
Workforce reductions     200,000          
Facility closure costs     200,000          
Other Operating Cost Reductions | Restructuring | Fiscal 2014 Charges                
Restructuring Cost and Reserve [Line Items]                
Workforce reductions       9,800,000        
Facility closure costs       600,000        
Non-cash impairment charge       $ 3,100,000     $ 3,100,000