Debt secured with a cross default feature.

No definition available.

Name:	cvlg_DebtSecuredWithACrossDefaultFeature
Namespace Prefix:	cvlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the fixed charge coverage requirement.

+ References

No definition available.

+ Details

Name:	cvlg_FixedChargeCoverageRequirement
Namespace Prefix:	cvlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The availability of line of credit facility as percentage of the revolver commitment.

+ References

No definition available.

+ Details

Name:	cvlg_LineOfCreditFacilityAvailabilityAsPercentageOfRevolverCommitment
Namespace Prefix:	cvlg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents percentage of aggregate commitments as borrowing capacity.

+ References

No definition available.

+ Details

Name:	cvlg_LineOfCreditFacilityBorrowingCapacityPercentageOfAggretaeCommitments
Namespace Prefix:	cvlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The maximum commitment value for a line of credit facility.

+ References

No definition available.

+ Details

Name:	cvlg_LineOfCreditFacilityMaximumCommitmentValue
Namespace Prefix:	cvlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility's maximum increase in borrowing capacity as long as no event of default exists.

+ References

No definition available.

+ Details

Name:	cvlg_LineOfCreditFacilityMaximumIncreaseInBorrowingCapacity
Namespace Prefix:	cvlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The revolver commitment amount.

+ References

No definition available.

+ Details

Name:	cvlg_LineOfCreditFacilityRevolverCommitmentAmount
Namespace Prefix:	cvlg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The percent of the lenders' aggregate commitments under the credit facility.

+ References

No definition available.

+ Details

Name:	cvlg_PercentOfAggregateCommitmentsUnderCreditFacility
Namespace Prefix:	cvlg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percent of appraised fair market value of eligible real estate used in the calculation of borrowing base.

+ References

No definition available.

+ Details

Name:	cvlg_PercentOfAppraisedFairMarketValueOfEligibleRealEstate
Namespace Prefix:	cvlg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percent of appraised net orderly liquidation value of eligible revenue equipment used in the calculation of borrowing base.

+ References

No definition available.

+ Details

Name:	cvlg_PercentOfAppraisedNetOrderlyLiquidationValueOfEligibleRevenueEquipment
Namespace Prefix:	cvlg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percent of the eligible accounts receivable used in the calculation of borrowing base.

+ References

No definition available.

+ Details

Name:	cvlg_PercentOfEligibleAccountsReceivable
Namespace Prefix:	cvlg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percent of net book value of eligible revenue equipment used in the calculation of borrowing base.

+ References

No definition available.

+ Details

Name:	cvlg_PercentOfNetBookValueOfEligibleRevenueEquipment
Namespace Prefix:	cvlg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
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-Name Accounting Standards Codification
-Topic 944
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-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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

- 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

+ 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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cvlg_LendersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=cvlg_FederalFundsRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=cvlg_ApplicableMarginMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cvlg_TBKBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cvlg_DrawNoteMember
Namespace Prefix:
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Note 7 - Debt (Details Textual) - USD ($) $ in Thousands			9 Months Ended
Note 7 - Debt (Details Textual) - USD ($) $ in Thousands	Oct. 23, 2020	Sep. 23, 2020	Sep. 30, 2020	Sep. 30, 2019	Apr. 30, 2020	Dec. 31, 2019	Aug. 31, 2015
Letters of Credit Outstanding, Amount			$ 36,700			$ 35,200
Interest Rate Swap [Member]
Derivative, Fixed Interest Rate							4.20%
Variable Rate Note [Member]
Debt Instrument, Face Amount							$ 28,000
Lenders [Member]
Line of Credit Facility, Maximum Borrowing Capacity			$ 95,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			0.25%
Percent of Eligible Accounts Receivable			85.00%
Percent of Appraised Net Orderly Liquidation, Value of Eligible Revenue Equipment			85.00%
Percent of Net Book Value of Eligible Revenue Equipment			95.00%
Line of Credit Facility, Availability as Percentage of Revolver Commitment			35.00%
Line of Credit Facility, Revolver Commitment, Amount			$ 45,000
Percent of Appraised Fair Market Value of Eligible Real Estate			75.00%
Long-term Line of Credit, Total			$ 0
Letters of Credit Outstanding, Amount			36,700
Line of Credit Facility, Remaining Borrowing Capacity			58,300
Fixed Charge Coverage Requirement			0	$ 0
Debt, Secured with a Cross Default Feature			$ 60,300		$ 177,300
Lenders [Member] \| Federal Funds Rate [Member] \| Base Rate Loans [Member]
Debt Instrument, Basis Spread on Variable Rate			0.50%
Lenders [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Base Rate Loans [Member]
Debt Instrument, Basis Spread on Variable Rate			1.00%
Lenders [Member] \| Applicable Margin [Member] \| Base Rate Loans [Member] \| Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate			0.50%
Lenders [Member] \| Applicable Margin [Member] \| Base Rate Loans [Member] \| Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate			1.00%
Lenders [Member] \| Applicable Margin [Member] \| LIBOR Loans [Member] \| Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate			1.50%
Lenders [Member] \| Applicable Margin [Member] \| LIBOR Loans [Member] \| Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate			2.00%
Lenders [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity			$ 95,000
Line of Credit Facility, Maximum Increase in Borrowing Capacity			50,000
Lenders [Member] \| Revolving Credit Facility [Member] \| Base Rate Loans [Member]
Long-term Line of Credit, Total			0
Lenders [Member] \| Letter of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity			95,000
Line of Credit Facility, Borrowing Capacity, Percentage of Aggregate Commitments			$ 10,000
Lenders [Member] \| Swing Line Sub Facility [Member]
Percent of Aggregate Commitments under Credit Facility			10.00%
Lenders [Member] \| Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 110,000
Percent of Eligible Accounts Receivable	87.50%
Percent of Net Book Value of Eligible Revenue Equipment	100.00%
Line of Credit Facility, Availability as Percentage of Revolver Commitment	40.90%
Line of Credit Facility, Maximum Commitment Value	$ 10,400
Percent of Appraised Fair Market Value of Eligible Real Estate	80.00%
Lenders [Member] \| Subsequent Event [Member] \| Applicable Margin [Member] \| Base Rate Loans [Member] \| Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Lenders [Member] \| Subsequent Event [Member] \| Applicable Margin [Member] \| Base Rate Loans [Member] \| Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Lenders [Member] \| Subsequent Event [Member] \| Applicable Margin [Member] \| LIBOR Loans [Member] \| Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Lenders [Member] \| Subsequent Event [Member] \| Applicable Margin [Member] \| LIBOR Loans [Member] \| Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Lenders [Member] \| Subsequent Event [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 110,000
Lenders [Member] \| Subsequent Event [Member] \| Letter of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 105,000
TBK Bank [Member] \| Draw Note [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 45,000
Debt Instrument, Collateral Amount		$ 60,000
TBK Bank [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Draw Note [Member]
Debt Instrument, Basis Spread on Variable Rate		1.50%
TBK Bank [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Draw Note [Member] \| Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate		0.25%