Goodwill and Intangible Assets - Activity of Goodwill by Reportable Operating Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Oct. 02, 2015	Sep. 26, 2014
Goodwill [Roll Forward]
Balance, beginning	$ 240,626	$ 225,300
Business combinations	49,200	19,100
Foreign currency translation adjustments	(6,300)	(3,800)
Balance, ending	283,452	240,626
Oncology Systems
Goodwill [Roll Forward]
Balance, beginning	148,300	132,000
Business combinations	10,500	16,300
Foreign currency translation adjustments	0	0
Balance, ending	158,800	148,300
Imaging Components
Goodwill [Roll Forward]
Balance, beginning	36,000	33,200
Business combinations	38,700	2,800
Foreign currency translation adjustments	0	0
Balance, ending	74,700	36,000
Other
Goodwill [Roll Forward]
Balance, beginning	56,300	60,100
Business combinations	0	0
Foreign currency translation adjustments	(6,300)	(3,800)
Balance, ending	$ 50,000	$ 56,300