Stockholders' Equity and Noncontrolling Interests - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at beginning of period	$ 1,521.9	$ 1,797.9
Balance at end of period	1,588.7	1,521.9
Stockholders' Equity Attributable to Redeemable Noncontrolling Interest
Balance at beginning of period	0.0	10.3
Net earnings attributable to noncontrolling interests		0.1
Transfer of redeemable noncontrolling interests in MeVis to Varex		(10.3)
Other		(0.1)
Balance at end of period		0.0
Noncontrolling Interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at beginning of period	4.3	3.7
Net earnings attributable to noncontrolling interests	0.4	0.6
Transfer of redeemable noncontrolling interests in MeVis to Varex	0.0	0.0
Other	(0.4)	0.0
Balance at end of period	$ 4.3	$ 4.3