STOCKHOLDERS' EQUITY AND NONCONTROLLING INTERESTS - Schedule of Amounts Reclassified Out of Other Comprehensive Earnings (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Comprehensive Income [Line Items]
Revenues	$ 709.1	$ 632.8	$ 2,117.5	$ 1,897.5
Net earnings attributable to Varian	72.6	69.7	33.5	139.9
Unrealized loss on defined benefit pension and post-retirement benefit plans
Reclassification Adjustment Out Of Accumulated Comprehensive Income [Line Items]
Cost of revenues & Operating expenses	(0.4)	(0.9)	(1.3)	(2.8)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Comprehensive Income [Line Items]
Net earnings attributable to Varian	(0.4)	(0.9)	(2.2)	(2.8)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized loss on cash flow hedging instruments
Reclassification Adjustment Out Of Accumulated Comprehensive Income [Line Items]
Revenues	$ 0.0	$ 0.0	$ (0.9)	$ 0.0