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PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Multiemployer Plans) (Details) - Multiemployer pension plans - Asset-Based | 3 Months Ended
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Mar. 31, 2018 plan
Multiemployer Plans |
Number of multiemployer plans to which ABF Freight currently contributes | 25
Maximum projected time to insolvency for plans in "critical and declining" status | 14 years
Maximum projected time to insolvency for plans in "critical and declining" status if additional criteria apply | 19 years
Threshold ratio of inactive to active participants for greater insolvency period to determine "critical and declining" status | 2
Threshold funded percentage for greater insolvency period to determine "critical and declining" status | 80.00%
Central States Pension Plan |
Multiemployer Plans |
Approximate proportion of multiemployer pension plan contributions (as a percent) | 50.00%

X
- Definition Represents the percentage of the entity's contributions to multiemployer pension plans that are made to the specified plan. + References No definition available. + Details
Name: | arcb_MultiemployerPensionPlansPercentageOfContributions
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The threshold funded percentage of plans, below which a higher maximum period for insolvency is used to determine "critical and declining" status. + References No definition available. + Details
Name: | arcb_MultiemployerPlansCriticalAndDecliningStatusThresholdFundedPercentageForGreaterInsolvencyPeriod
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The threshold ratio of inactive participants to active participants, above which a higher maximum period for insolvency is used to determine "critical and declining" status. + References No definition available. + Details
Name: | arcb_MultiemployerPlansCriticalAndDecliningStatusThresholdRatioOfInactiveToActiveParticipantsForGreaterInsolvencyPeriod
Namespace Prefix: | arcb_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum period within which a plan in "critical and declining" status is expected to become insolvent, unless additional criteria relating to ratio of inactive to active participants or funded percentage are applicable. + References No definition available. + Details
Name: | arcb_MultiemployerPlansMaximumPeriodOfExpectedInsolvencyForCriticalAndDecliningStatus
Namespace Prefix: | arcb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum period within which a plan in "critical and declining" status is expected to become insolvent, if additional criteria relating to ratio of inactive to active participants or funded percentage are applicable. + References No definition available. + Details
Name: | arcb_MultiemployerPlansMaximumPeriodOfExpectedInsolvencyForCriticalAndDecliningStatusIfAdditionalCriteriaApply
Namespace Prefix: | arcb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of multiemployer plans to which the reporting entity currently contributes. + References No definition available. + Details
Name: | arcb_MultiemployerPlansNumber
Namespace Prefix: | arcb_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_MultiemployerPlansAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_MultiemployerPlanTypeAxis=us-gaap_MultiemployerPlansPensionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=arcb_AssetBasedSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MultiemployerPlanNameAxis=arcb_CentralStatesPensionPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |