Quarterly Financial Data - Schedule of Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jul. 01, 2016	Apr. 01, 2016	Jan. 01, 2016	Oct. 02, 2015	Jul. 03, 2015	Apr. 03, 2015	Jan. 02, 2015	Sep. 30, 2016	Oct. 02, 2015	Sep. 26, 2014
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 912.5	$ 789.4	$ 758.8	$ 757.1	$ 817.8	$ 784.0	$ 759.4	$ 737.9	$ 3,217.8	$ 3,099.1	$ 3,049.8
Gross margin	388.0	346.4	317.2	309.7	318.2	315.0	322.5	327.0	1,361.3	1,282.7	1,301.7
Net earnings attributable to Varian	$ 117.5	$ 98.8	$ 97.0	$ 89.0	$ 98.7	$ 113.5	$ 106.0	$ 93.3	$ 402.3	$ 411.5	$ 403.7
Net earnings per share – basic: (in dollars per share)	$ 1.25	$ 1.04	$ 1.01	$ 0.92	$ 1.00	$ 1.14	$ 1.06	$ 0.93	$ 4.22	$ 4.13	$ 3.88
Net earnings per share – diluted: (in dollars per share)	$ 1.24	$ 1.04	$ 1.01	$ 0.91	$ 0.99	$ 1.13	$ 1.05	$ 0.92	$ 4.19	$ 4.09	$ 3.83
Separation costs	$ 11.5	$ 5.4							$ 16.9	$ 0.0	$ 0.0