XML 76 R91.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

EMPLOYEE BENEFIT PLANS (Multiemployer Plans) (Details) $ in Thousands |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 01, 2019 | Jan. 31, 2019 | Aug. 01, 2018 | Feb. 01, 2018 | Jan. 31, 2018 | Aug. 01, 2017 | Feb. 01, 2017 | Jun. 30, 2018 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Dec. 31, 2019 USD ($) plan | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jan. 01, 2018 | Jan. 01, 2017
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer pension fund withdrawal liability charge (pre-tax) |  |  |  |  |  |  |  |  |  | $ 37,900 |  | $ 37,922 |  |  |
Asset-Based |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum funded percentage of plans in green zone |  |  |  |  |  |  |  |  |  |  | 80.00% |  |  |  |
Asset-Based | Multiemployer pension plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of multiemployer plans to which ABF Freight currently contributes | plan |  |  |  |  |  |  |  |  |  |  | 25 |  |  |  |
Maximum funded percentage of plans in yellow zone |  |  |  |  |  |  |  |  |  |  | 80.00% |  |  |  |
Maximum funded percentage of plans in red zone |  |  |  |  |  |  |  |  |  |  | 65.00% |  |  |  |
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% |  |  |  |
Percentage of contributions to the multiemployer pension plans that are in critical and declining status |  |  |  |  |  |  |  |  |  |  | 57.00% |  |  |  |
Percentage of contributions to the multiemployer pension plans that are in critical status |  |  |  |  |  |  |  |  |  |  | 3.00% |  |  |  |
Percentage of contributions to the multiemployer pension plans that are in endangered status |  |  |  |  |  |  |  |  |  |  | 4.00% |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | $ 153,746 | 167,249 | $ 158,416 |  |
Asset-Based | Multiemployer pension plans | Central States Pension Plan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | $ 75,803 | $ 74,177 | $ 78,230 |  |
Threshold percentage of the entity's contributions relative to total fund contributions, which was exceeded during the period |  |  |  |  |  |  |  |  |  |  |  | 5.00% | 5.00% |  |
Maximum projected time to insolvency without legislative action |  |  |  |  |  |  |  |  |  |  | 6 years |  |  |  |
Percentage of contributions to multiemployer pension plan |  |  |  |  |  |  |  |  |  |  | 50.00% | 50.00% | 50.00% |  |
Actuarially certified projected funded percentage of multiemployer pension plan |  |  |  |  |  |  |  |  |  |  |  |  |  | 27.20% | 37.80%
Asset-Based | Multiemployer pension plans | Western Conference of Teamsters Pension Plan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | $ 24,860 | $ 25,268 | $ 26,320 |  |
Asset-Based | Multiemployer pension plans | Central Pennsylvania Teamsters Pension Plan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | 13,907 | $ 13,393 | $ 13,391 |  |
Threshold percentage of the entity's contributions relative to total fund contributions, which was exceeded during the period |  |  |  |  |  |  |  |  |  |  |  | 5.00% | 5.00% |  |
Asset-Based | Multiemployer pension plans | Local 710 Pension Fund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | 10,164 | $ 9,929 | $ 10,054 |  |
Threshold percentage of the entity's contributions relative to total fund contributions, which was exceeded during the period |  | 5.00% |  | 5.00% | 5.00% |  | 5.00% |  |  |  |  |  |  |  |
Asset-Based | Multiemployer pension plans | New England Pension Fund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | 4,802 | 20,090 | 5,026 |  |
Contributions to multiemployer plans related to pension fund withdrawal liability |  |  |  |  |  |  |  |  |  |  | 1,600 | 15,700 |  |  |
Contribution rate frozen period (in years) |  |  | 10 years |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer pension fund withdrawal liability charge (pre-tax) |  |  |  |  |  |  |  | $ 37,900 |  |  |  |  |  |  |
Initial lump sum payment of withdrawal liability |  |  |  |  |  |  |  |  | $ 15,100 |  |  |  |  |  |
Withdrawal liability monthly payments period (in years) |  |  |  |  |  |  |  |  | 23 years |  |  |  |  |  |
Aggregate present value of monthly payments |  |  |  |  |  |  |  |  | $ 22,800 |  |  |  |  |  |
Outstanding withdrawal liability |  |  |  |  |  |  |  |  |  |  | 22,000 |  |  |  |
Fair value of withdrawal obligation |  |  |  |  |  |  |  |  |  |  | $ 24,500 |  |  |  |
Discount rate using 20-year U.S. Treasury (as a percent) |  |  |  |  |  |  |  |  |  |  | 3.40% |  |  |  |
Asset-Based | Multiemployer pension plans | New England Pension Fund | Accrued expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding withdrawal liability |  |  |  |  |  |  |  |  |  |  | $ 600 |  |  |  |
Asset-Based | Multiemployer pension plans | New England Pension Fund | Other long-term liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding withdrawal liability |  |  |  |  |  |  |  |  |  |  | 21,400 |  |  |  |
Asset-Based | Multiemployer pension plans | All Other Pension Plans in Aggregate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | $ 24,210 | 24,392 | 25,395 |  |
Asset-Based | Multiemployer pension plans | 707 Pension Fund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of contributions to multiemployer pension plan |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |
Asset-Based | Multiemployer pension plans | New York State Pension Fund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of contributions to multiemployer pension plan |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |
Asset-Based | Multiemployer pension plans | Western Pennsylvania Teamsters and Employers Pension Fund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of contributions to multiemployer pension plan |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |
Asset-Based | Multiemployer health and welfare plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of multiemployer plans to which ABF Freight currently contributes | plan |  |  |  |  |  |  |  |  |  |  | 38 |  |  |  |
Total contributions to multiemployer plans |  |  |  |  |  |  |  |  |  |  | $ 172,000 | $ 162,100 | $ 162,200 |  |
Percentage increase in contribution rate for time worked related to benefit costs | 4.00% |  | 4.10% |  |  | 3.70% |  |  |  |  |  |  |  |  |
Asset-Based | Unionized employees concentration risk | Number of employees |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Asset-Based segment employees covered under collective bargaining agreement with the IBT |  |  |  |  |  |  |  |  |  |  | 82.00% |  |  |  |

X
- Definition Amount of pre-tax expenses associated with multiemployer pension fund withdrawal liability. + References No definition available. + Details
Name: | arcb_MultiemployerPensionFundWithdrawalLiabilityCharge
Namespace Prefix: | arcb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the projected funded percentage of a specified multiemployer pension plan. + References No definition available. + Details
Name: | arcb_MultiemployerPensionPlanFundedPercentage
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the maximum funded percentage of plans in the red zone. + References No definition available. + Details
Name: | arcb_MultiemployerPensionPlansMaximumFundedPercentageOfPlansInRedZone
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the maximum funded percentage of plans in the yellow zone. + References No definition available. + Details
Name: | arcb_MultiemployerPensionPlansMaximumFundedPercentageOfPlansInYellowZone
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the minimum funded percentage of plans in the yellow zone. + References No definition available. + Details
Name: | arcb_MultiemployerPensionPlansMinimumFundedPercentageOfPlansInGreenZone
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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 Represents the percentage of the entity's contributions to multiemployer pension plans that are made to plans in critical and declining status. + References No definition available. + Details
Name: | arcb_MultiemployerPensionPlansPercentageOfContributionsToPlansInCriticalAndDecliningStatus
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

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

X
- Definition Amount of contributions made to multiemployer plan by employer related to pension fund withdrawal liability. + References No definition available. + Details
Name: | arcb_MultiemployerPlanContributionsByEmployerWithdrawalLiabilityCharge
Namespace Prefix: | arcb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the threshold percentage of the entity's contributions to the plan relative to total contributions received by the plan, which was exceeded during the period, triggering disclosure of the plan year. + References No definition available. + Details
Name: | arcb_MultiemployerPlanMinimumPercentageThresholdOfContributionsToTotalPlanContributionsReceivedByPensionFund
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Discount rate applied to the undiscounted amount of future payments due to determine the present value of the multiemployer plan withdrawal liability recorded as of the balance sheet date. + References No definition available. + Details
Name: | arcb_MultiemployerPlanWithdrawalLiabilityDiscountRatePercent
Namespace Prefix: | arcb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The period for which contribution rate is frozen under multiemployer plan agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | arcb_MultiemployerPlansContributionRateFrozenPeriod
Namespace Prefix: | arcb_
Data Type: | xbrli:durationItemType
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 The maximum period within which a plan is expected to become insolvent without legislation action. + References No definition available. + Details
Name: | arcb_MultiemployerPlansMaximumPeriodOfExpectedInsolvencyWithoutLegislativeAction
Namespace Prefix: | arcb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The period of time over which monthly payments have to be made for withdrawal liability settlement for multiemployer plan, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | arcb_MultiemployerPlansMonthlyPaymentsSettlementPeriod
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
- Definition Amount of cash outflow for initial lumpsum payment of withdrawal liability from multiemployer plan. + References No definition available. + Details
Name: | arcb_MultiemployerPlansWithdrawalLiabilityInitialLumpsumPayment
Namespace Prefix: | arcb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The aggregate present value of the monthly payments for the multiemployer plan withdrawal liability. + References No definition available. + Details
Name: | arcb_MultiemployerPlansWithdrawalLiabilityMonthlyPaymentsAggregatePresentValue
Namespace Prefix: | arcb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value of the obligation recognized by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References No definition available. + Details
Name: | arcb_MultiemployerPlansWithdrawalObligationFairValue
Namespace Prefix: | arcb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13531-108611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13537-108611 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592 + Details
Name: | us-gaap_ConcentrationRiskPercentage1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Increase (decrease) in employer's contractual contribution rate to multiemployer plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450673-114947 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947 + Details
Name: | us-gaap_MultiemployerPlanContributionRateIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of contributions made to multiemployer plan by employer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450691-114947 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
Name: | us-gaap_MultiemployerPlanContributionsByEmployer
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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
- Definition Amount of the obligation recognized by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References No definition available. + Details
Name: | us-gaap_MultiemployerPlansWithdrawalObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Details
Name: | us-gaap_MultiemployerPlanTypeAxis=us-gaap_MultiemployerPlansPensionMember
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: |

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

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

X
- Details
Name: | us-gaap_MultiemployerPlanNameAxis=arcb_Local710PensionFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_AccruedLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_MultiemployerPlanNameAxis=arcb_Local707PensionFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_UnionizedEmployeesConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_NumberOfEmployeesTotalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |