Business Segments and Geographic Information - Additional Information (Detail) (USD $)	3 Months Ended									12 Months Ended
	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 29, 2012	Sep. 29, 2012	Sep. 27, 2014 Segment	Sep. 28, 2013	Sep. 29, 2012
Segment Reporting Disclosure [Line Items]
Number of reportable segments										4
Revenues	$ 660,600,000	$ 632,600,000	$ 625,000,000	$ 612,400,000	$ 622,100,000	$ 626,100,000	$ 612,700,000	$ 631,400,000		$ 2,530,700,000	$ 2,492,300,000	$ 2,002,600,000
Impairment of goodwill					1,100,000,000				5,800,000	0	1,117,400,000	5,800,000
Intersegment [Member]
Segment Reporting Disclosure [Line Items]
Revenues		0				0				0	0
Diagnostics [Member]
Segment Reporting Disclosure [Line Items]
Revenues										1,186,800,000	1,189,800,000	718,100,000
Impairment of goodwill										0
Breast Health [Member]
Segment Reporting Disclosure [Line Items]
Revenues										944,700,000	905,100,000	875,800,000
Impairment of goodwill										$ 0