Long-Term Debt (ABL Amendment) (Details) - ABL Amendment [Member] - Asset based lending facility [Member] - ABL Facility due 2021 [Member]	Jun. 10, 2016 USD ($)
Debt Instrument [Line Items]
Credit facility, decrease in borrowing capacity	$ 50,000,000
Credit facility, borrowing capacity	190,000,000
Amount of outstanding senior secured debt triggering a springing maturity	10,000,000.0
Unamortized debt issuance costs	$ 2,300,000

Debt, Amount of Outstanding Senior Secured Debt Triggering a Springing Maturity

No definition available.

Name:	cvo_DebtAmountofOutstandingSeniorSecuredDebtTriggeringaSpringingMaturity
Namespace Prefix:	cvo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Borrowing Capacity, Reduction

+ References

No definition available.

+ Details

Name:	cvo_LineofCreditFacilityBorrowingCapacityReduction
Namespace Prefix:	cvo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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_DebtInstrumentLineItems
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

+ Details

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

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	cvo_DebtTransactionsAxis=cvo_ABLAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cvo_ABLRevolvingCreditFacilityDue2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: