Reconciliation of Segment Operating Results to Companys Earnings from Continuing Operations before Taxes (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 26, 2014	Sep. 27, 2013	Sep. 28, 2012
Segment Reporting Information [Line Items]
Earnings from operations before taxes	$ 574.5	$ 612.1	$ 595.9
Interest income, net	3.3	3.2	1.8
Corporate
Segment Reporting Information [Line Items]
Earnings from operations before taxes	(41.5)	(22.3)	(9.6)
Operating Segments | Oncology Systems
Segment Reporting Information [Line Items]
Earnings from operations before taxes	495.5	512.0	505.4
Operating Segments | Imaging Components
Segment Reporting Information [Line Items]
Earnings from operations before taxes	169.9	165.6	142.5
Operating Segments | Total Reportable Segments
Segment Reporting Information [Line Items]
Earnings from operations before taxes	665.4	677.6	647.9
Operating Segments | Other
Segment Reporting Information [Line Items]
Earnings from operations before taxes	$ (52.7)	$ (46.4)	$ (44.2)