EARNINGS PER SHARE - Computation of Net Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Earnings Per Share [Abstract]
Net earnings	$ 29.5	$ 72.5	$ 221.8	$ 33.5
Less: Net earnings (loss) attributable to noncontrolling interests	0.1	(0.1)	0.6	0.0
Net earnings attributable to Varian	$ 29.4	$ 72.6	$ 221.2	$ 33.5
Weighted average shares outstanding - basic (in shares)	91.0	91.5	91.0	91.6
Dilutive effect of potential common shares (in shares)	0.8	1.0	0.9	1.0
Weighted average shares outstanding - diluted (in shares)	91.8	92.5	91.9	92.6
Net earnings per share attributable to Varian - basic (in dollars per share)	$ 0.32	$ 0.79	$ 2.43	$ 0.37
Net earnings per share attributable to Varian - diluted (in dollars per share)	$ 0.32	$ 0.79	$ 2.41	$ 0.36
Anti-dilutive employee shared based awards, excluded (in shares)	0.5	0.7	0.8	0.7