RELATED PARTY TRANSACTIONS - Additional Information (Detail) - dpiX Holding - Affiliated Entity $ in Millions	3 Months Ended	9 Months Ended
Jul. 01, 2016 USD ($) member	Jul. 03, 2015 USD ($)	Jul. 01, 2016 USD ($) member	Jul. 03, 2015 USD ($)	Oct. 02, 2015 USD ($)
Related Party Transaction [Line Items]
Ownership interest in dpiX Holding LLC (as a percent)	40.00%		40.00%
Number of members \| member	2		2
dpiX Holding LLC's ownership interest in dpiX LLC (as a percent)	100.00%		100.00%
Income (Loss) on equity investment in affiliate	$ (0.8)		$ (0.9)	$ 0.5
Carrying value of the equity investment in dpiX Holding	47.8		47.8		$ 47.3
Purchases of glass transistor arrays from dpiX	6.4	$ 5.6	$ 16.8	$ 15.5
Percentage of manufacturing capacity			50.00%
Percentage of fixed costs			50.00%
Fixed cost commitments	$ 9.0		$ 9.0

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.12)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 9
-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 11
-Article 7

+ Details

Name:	us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of fixed manufacturing costs required to be paid during the calendar year.

+ References

No definition available.

+ Details

Name:	var_FixedCostCommitments
Namespace Prefix:	var_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage of fixed costs as defined in the agreement and determined at the beginning of each calendar year that the entity is required to pay.

+ References

No definition available.

+ Details

Name:	var_PercentageOfFixedCosts
Namespace Prefix:	var_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of manufacturing capacity that the entity has the guaranteed right to purchase up to.

+ References

No definition available.

+ Details

Name:	var_PercentageOfManufacturingCapacity
Namespace Prefix:	var_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of dpiX Holding LLC's ownership interest in dpiX LLC.

+ References

No definition available.

+ Details

Name:	var_PercentageOfSubsidiaryOwnership
Namespace Prefix:	var_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Related Party Transaction, Number Of Consortium Members

+ References

No definition available.

+ Details

Name:	var_RelatedPartyTransactionNumberOfConsortiumMembers
Namespace Prefix:	var_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_CounterpartyNameAxis=var_DpiXHoldingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: