Value of input used to measure financial instrument.

No definition available.

Name:	arcb_FinancialInstrumentMeasurementInput
Namespace Prefix:	arcb_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Indicates measurement input for financial instrument.

+ References

No definition available.

+ Details

Name:	arcb_FinancialInstrumentMeasurementInputExtensibleEnumeration
Namespace Prefix:	arcb_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	duration

- 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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

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

- 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

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-15

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_NotesPayableOtherPayablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=arcb_NewEnglandPensionFundWithdrawalLiabilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
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FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Financial instruments (Details) $ in Thousands		9 Months Ended		12 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Fair value disclosure
Repayment of debt		$ 102,366	$ 52,489
Outstanding withdrawal liability	$ 18,900	18,900
Accrued expenses
Fair value disclosure
Outstanding withdrawal liability	800	800
Carrying Value
Fair value disclosure
Financial instruments	199,368	199,368		$ 248,340
Fair Value \| Level 2
Fair value disclosure
Financial instruments	199,264	199,264		245,369
Credit Facility
Fair value disclosure
Repayment of debt	50,000
Credit Facility \| Carrying Value
Fair value disclosure
Financial instruments				50,000
Credit Facility \| Fair Value \| Level 2
Fair value disclosure
Financial instruments				50,000
Notes payable \| Carrying Value
Fair value disclosure
Financial instruments	180,511	180,511		178,938
Notes payable \| Fair Value \| Level 2
Fair value disclosure
Financial instruments	181,503	181,503		177,149
New England Pension Fund withdrawal liability \| Carrying Value
Fair value disclosure
Financial instruments	18,857	18,857		19,402
New England Pension Fund withdrawal liability \| Fair Value \| Level 2
Fair value disclosure
Financial instruments	$ 17,761	$ 17,761		$ 18,220
Measurement input	0.053	0.053		0.053
Financial Instrument, Measurement Input		us-gaap:MeasurementInputDiscountRateMember		us-gaap:MeasurementInputDiscountRateMember