Credit Facilities - Additional Information (Detail)	12 Months Ended					1 Months Ended										12 Months Ended
	Sep. 28, 2012 USD ($)	Sep. 30, 2011 USD ($)	Oct. 01, 2010 USD ($)	Sep. 30, 2011 Amended Bofa Credit Facility USD ($)	Sep. 28, 2012 Japanese Line Of Credit Facility JPY (¥)	Sep. 28, 2012 Two Thousand Twelve Credit Facility USD ($)	Apr. 27, 2012 Two Thousand Twelve Credit Facility USD ($) Y	Apr. 27, 2012 Two Thousand Twelve Credit Facility Minimum	Apr. 27, 2012 Two Thousand Twelve Credit Facility Maximum	Apr. 27, 2012 Two Thousand Twelve Credit Facility Interest Accrued Description One	Apr. 27, 2012 Two Thousand Twelve Credit Facility Interest Accrued Description One Minimum	Apr. 27, 2012 Two Thousand Twelve Credit Facility Interest Accrued Description One Maximum	Apr. 27, 2012 Two Thousand Twelve Credit Facility Interest Accrued Description Two	Apr. 27, 2012 Two Thousand Twelve Credit Facility Interest Accrued Description Two Minimum	Apr. 27, 2012 Two Thousand Twelve Credit Facility Interest Accrued Description Two Maximum	Sep. 28, 2012 Sumitomo Credit Facility JPY (¥)
Line of Credit Facility [Line Items]
Credit facility, term							5
Loan facility, maximum borrowing capacity				$ 300,000,000	¥ 2,700,000,000		$ 300,000,000									¥ 3,000,000,000
Maximum amount that can be used to support letters of credit				25,000,000			50,000,000
Maximum amount permitted for swing line loans							25,000,000
Loan facility, maximum increase to aggregate commitments							200,000,000
Percentage of Varian Medical Systems Nederland Holdings B.V. voting shares pledged						65.00%
Line of credit, interest rate calculation (Eurodollar rate margin)											1.25%	1.50%
Margin added if base rate is based on federal funds rate													0.50%
Line of credit, interest rate calculation										Eurodollar rate (as defined in the credit agreement), plus a margin of 1.25% to 1.5% based on a leverage ratio involving funded indebtedness and earnings before interest, taxes and depreciation and amortization ("EBITDA" )			Based upon a base rate of the highest of (a) the federal funds rate plus 0.5%, (b) BofA's announced prime rate or (c) the Eurodollar rate plus 1%, plus a margin of 0.25% to 0.5% based on the same leverage ratio			Basic loan rate announced by the Bank of Japan plus a margin of 0.5% per annum.
Margin added if base rate is based on Eurodollar rate													1.00%
Line of credit, interest rate calculation (base rate margin)														0.25%	0.50%
Commitment fees at an annual rate								0.25%	0.30%
Line of credit, commitment fee							0.25% to 0.30% based on the same leverage ratio
Line of credit, amount outstanding				181,000,000		155,000,000
Line of credit, interest rate				1.05%		1.47%
Line of credit facility, maturity date																Feb. 28, 2013
Line of credit, interest rate calculation (Bank of Japan basis loan rate margin)																0.50%
Line of Credit, interest paid	2,500,000	800,000	300,000
Line of Credit, commitment fees amount	$ 320,000	$ 332,000	$ 231,000