Discontinued Operations - Income Statement Disclosures (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net earnings (loss) from discontinued operations	$ 0.0	$ 0.0	$ (13.3)	$ 6.5	$ 0.0	$ (6.8)	$ 77.4
Less: Net earnings from discontinued operations attributable to noncontrolling interests					0.0	0.1	0.5
Net earnings (loss) from discontinued operations attributable to Varian					$ 0.0	(6.9)	76.9
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues						194.0	596.7
Cost of revenues						117.3	348.3
Gross margin						76.7	248.4
Operating expenses						76.1	132.6
Operating earnings						0.6	115.8
Taxes on earnings						7.4	38.4
Net earnings (loss) from discontinued operations						(6.8)	77.4
Less: Net earnings from discontinued operations attributable to noncontrolling interests						0.1	0.5
Net earnings (loss) from discontinued operations attributable to Varian						(6.9)	76.9
Separation costs						$ 34.2	$ 16.9