The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

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

- Definition

Credit Facility Term

+ References

No definition available.

+ Details

Name:	vrts_CreditFacilityTerm
Namespace Prefix:	vrts_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Leverage Ratio Description

+ References

No definition available.

+ Details

Name:	vrts_LeverageRatioDescription
Namespace Prefix:	vrts_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line Of Credit Facility Basis Spread On Alternate Base Rate

+ References

No definition available.

+ Details

Name:	vrts_LineOfCreditFacilityBasisSpreadOnAlternateBaseRate
Namespace Prefix:	vrts_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility Description of London Inter Bank Offered Rate

+ References

No definition available.

+ Details

Name:	vrts_LineOfCreditFacilityDescriptionOfLondonInterBankOfferedRate
Namespace Prefix:	vrts_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line Of Credit Facility Increase Additional Borrowings On Condition Satisfaction

+ References

No definition available.

+ Details

Name:	vrts_LineOfCreditFacilityIncreaseAdditionalBorrowingsOnConditionSatisfaction
Namespace Prefix:	vrts_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum Leverage Ratio

+ References

No definition available.

+ Details

Name:	vrts_MaximumLeverageRatio
Namespace Prefix:	vrts_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum Interest Coverage Ratio One

+ References

No definition available.

+ Details

Name:	vrts_MinimumInterestCoverageRatioOne
Namespace Prefix:	vrts_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum Interest Coverage Ratio Under Credit Facility

+ References

No definition available.

+ Details

Name:	vrts_MinimumInterestCoverageRatioUnderCreditFacility
Namespace Prefix:	vrts_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Detail) (USD $)	12 Months Ended	3 Months Ended
Debt - Additional Information (Detail) (USD $)	Dec. 31, 2014	Sep. 30, 2013	Dec. 31, 2013
Line of Credit Facility [Line Items]
Term for credit facility	5 years
Outstanding under the Credit Facility	$ 0us-gaap_LineOfCredit		$ 0us-gaap_LineOfCredit
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Limit for the issuance of standby letters of credit	7,500,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Borrowing capacity	75,000,000
Credit facility amount increase in borrowing capacity on condition	50,000,000
Repayment of debt		15,000,000
Remaining borrowing capacity	$ 75,000,000
Credit facility interest periods	One, two, three or six months
Minimum interest coverage ratio	At least 4.00:1
Minimum percentage of interest adjustment	4.00
Leverage ratio	No greater than 2.75:1
Maximum indebtedness to EBITDA	2.75
Revolving Credit Facility [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Percentage of margin on principal amount	2.50%
Commitment fee	0.50%
Revolving Credit Facility [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Percentage of margin on principal amount	0.75%
Commitment fee	0.35%