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
	Jan. 03, 2020	Dec. 28, 2018
Earnings Per Share [Abstract]
Net earnings	$ 88.9	$ 103.9
Less: Net earnings attributable to noncontrolling interests	0.7	0.7
Net earnings attributable to Varian	$ 88.2	$ 103.2
Weighted average shares outstanding - basic (in shares)	90.9	91.0
Dilutive effect of potential common shares (in shares)	0.8	1.0
Weighted average shares outstanding - diluted (in shares)	91.7	92.0
Net earnings per share attributable to Varian - basic (in dollars per share)	$ 0.97	$ 1.13
Net earnings per share attributable to Varian - diluted (in dollars per share)	$ 0.96	$ 1.12
Anti-dilutive employee shared based awards, excluded (in shares)	0.8	0.9