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