Note 1 - Significant Accounting Policies (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2017	Sep. 30, 2016
Tractors [Member]
Property, Plant and Equipment, Useful Life	5 years
Property, Plant and Equipment, Salvage Value, Percentage	15.00%
Tractors [Member] \| Salvage Value [Member]
Depreciation, Additional Expense		$ 2.0
Depreciation, Additional Expense, After Tax		$ 1.2
Effect of Additional Depreciation Expense on Earnings Per Share		$ 0.06
Refrigerated Trailers [Member]
Property, Plant and Equipment, Useful Life	7 years
Dry Van Trailers [Member]
Property, Plant and Equipment, Useful Life	10 years
Property, Plant and Equipment, Salvage Value, Percentage	25.00%
Revenue Equipment [Member] \| Minimum [Member]
Capital Leases of Lessee, Term of Contract	5 years
Revenue Equipment [Member] \| Maximum [Member]
Capital Leases of Lessee, Term of Contract	7 years

Term of the capital leases' leasing arrangement.

No definition available.

Name:	cvti_CapitalLeasesOfLesseeTermOfContract
Namespace Prefix:	cvti_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of additional depreciation expense per quarter due to changes in accounting estimate.

+ References

No definition available.

+ Details

Name:	cvti_DepreciationAdditionalExpense
Namespace Prefix:	cvti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of additional depreciation expense per quarter net of tax due to changes in accounting estimate.

+ References

No definition available.

+ Details

Name:	cvti_DepreciationAdditionalExpenseAfterTax
Namespace Prefix:	cvti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Effect of additional depreciation expense on quarterly earnings per share due to changes in accounting estimate.

+ References

No definition available.

+ Details

Name:	cvti_EffectOfAdditionalDepreciationExpenseOnEarningsPerShare
Namespace Prefix:	cvti_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Stated as a percentage, the estimated or actual value of the asset at the end of its useful life or when it is no longer serviceable (cannot be used for its original purpose) divided by its [historical] capitalized cost.

+ References

No definition available.

+ Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cvti_TractorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ChangeInAccountingEstimateByTypeAxis=us-gaap_SalvageValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cvti_RefrigeratedTrailersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cvti_DryVanTrailersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cvti_RevenueEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: