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		6 Months Ended
	Mar. 31, 2017	Apr. 01, 2016	Mar. 31, 2017	Apr. 01, 2016
Earnings Per Share [Abstract]
Net earnings from continuing operations	$ 69.3	$ 77.2	$ 83.8	$ 149.1
Less: Net earnings (loss) from continuing operations attributable to noncontrolling interests	(0.1)	(0.1)	0.4	0.0
Net earnings from continuing operations attributable to Varian	69.4	77.3	83.4	149.1
Net (loss) earnings from discontinued operations	(13.3)	19.8	(6.8)	36.9
Less: Net earnings from discontinued operations attributable to noncontrolling interests	0.0	0.1	0.1	0.0
Net (loss) earnings from discontinued operations attributable to Varian	(13.3)	19.7	(6.9)	36.9
Net earnings attributable to Varian	$ 56.1	$ 97.0	$ 76.5	$ 186.0
Weighted average shares outstanding - basic (in shares)	93.0	95.7	93.2	96.5
Dilutive effect of potential common shares (in shares)	0.7	0.5	0.7	0.6
Weighted average shares outstanding - diluted (in shares)	93.7	96.2	93.9	97.1
Net earnings per share - basic - Continuing operations (in dollars per share)	$ 0.75	$ 0.81	$ 0.90	$ 1.55
Net earnings per share - basic - Discontinued operations (in dollars per share)	(0.15)	0.20	(0.08)	0.38
Net earnings per share - basic (in dollars per share)	0.60	1.01	0.82	1.93
Net earnings per share - diluted - Continuing operations (in dollars per share)	0.74	0.80	0.89	1.54
Net earnings per share - diluted - Discontinued operations (in dollars per share)	(0.14)	0.21	(0.08)	0.38
Net earnings per share - diluted (in dollars per share)	$ 0.60	$ 1.01	$ 0.81	$ 1.92
Anti-dilutive employee shared based awards, excluded (in shares)	0.6	2.0	0.6	2.0