CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Capital in Excess of Par Value	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Total Varian Stockholders' Equity	Total Varian Stockholders' Equity Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interests
Beginning balance (in shares) at Sep. 27, 2019			90.8
Balance at beginning of period at Sep. 27, 2019	$ 1,777.6		$ 90.8	$ 845.6	$ 934.0		$ (102.1)	$ 1,768.3		$ 9.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	88.9				88.2			88.2		0.7
Other comprehensive earnings (loss)	5.1						5.1	5.1
Issuance of common stock (in shares)			0.3
Issuance of common stock	21.0		$ 0.3	20.7				21.0
Tax withholdings on vesting of equity awards	(3.6)			(3.6)				(3.6)
Share-based compensation expense	$ 14.7			14.7				14.7
Repurchases of common stock (in shares)	(0.3)		(0.4)
Repurchases of common stock	$ (46.4)		$ (0.4)	(7.0)	(39.0)			(46.4)
Ending balance (in shares) at Jan. 03, 2020			90.7
Balance at end of period at Jan. 03, 2020	1,857.3		$ 90.7	870.4	983.2		(97.0)	1,847.3		10.0
Beginning balance (in shares) at Sep. 27, 2019			90.8
Balance at beginning of period at Sep. 27, 2019	$ 1,777.6		$ 90.8	845.6	934.0		(102.1)	1,768.3		9.3
Ending balance (in shares) at Oct. 02, 2020	91.2		91.2
Balance at end of period at Oct. 02, 2020	$ 2,084.8	$ (3.9)	$ 91.2	937.0	1,133.0	$ (3.9)	(85.7)	2,075.5	$ (3.9)	9.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Net earnings (loss)	$ 96.8				96.5			96.5		0.3
Other comprehensive earnings (loss)	8.9						8.9	8.9
Issuance of common stock (in shares)			0.6
Issuance of common stock	52.4		$ 0.6	51.8				52.4
Tax withholdings on vesting of equity awards	(7.6)			(7.6)				(7.6)
Share-based compensation expense	$ 16.5			16.5				16.5
Repurchases of common stock (in shares)	0.0
Other	$ (0.1)									(0.1)
Ending balance (in shares) at Jan. 01, 2021	91.8		91.8
Balance at end of period at Jan. 01, 2021	$ 2,247.8		$ 91.8	$ 997.7	$ 1,225.6		$ (76.8)	$ 2,238.3		$ 9.5