Earnings Per Share - Computation of Net Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended							9 Months Ended	12 Months Ended
	Oct. 02, 2015	Apr. 03, 2015	Jan. 02, 2015	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014	Dec. 27, 2013	Jul. 03, 2015	Oct. 02, 2015	Sep. 26, 2014	Sep. 27, 2013
Earnings Per Share [Abstract]
Net earnings attributable to Varian	$ 98,700	$ 106,000	$ 93,300	$ 105,900	$ 107,100	$ 92,700	$ 98,000	$ 113,500	$ 411,485	$ 403,703	$ 438,248
Weighted average shares outstanding - basic (in shares)									99,679	103,964	108,352
Dilutive effect of potential common shares (in shares)									873	1,307	1,701
Weighted average shares outstanding - diluted (in shares)									100,552	105,271	110,053
Net earnings per share - basic (in dollars per share)	$ 1.00	$ 1.06	$ 0.93	$ 1.04	$ 1.03	$ 0.89	$ 0.92	$ 1.14	$ 4.13	$ 3.88	$ 4.04
Net earnings per share - diluted (in dollars per share)	$ 0.99	$ 1.05	$ 0.92	$ 1.02	$ 1.02	$ 0.88	$ 0.91	$ 1.13	$ 4.09	$ 3.83	$ 3.98
Anti-dilutive employee shared based awards, excluded (in shares)									987	632	707