Value of input used to measure financial instrument.

No definition available.

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Namespace Prefix:	arcb_
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Balance Type:	na
Period Type:	instant

- Definition

Indicates measurement input for financial instrument.

+ References

No definition available.

+ Details

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Data Type:	enum2:enumerationSetItemType
Balance Type:	na
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- 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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- 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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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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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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- Details

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Data Type:	na
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- Details

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Data Type:	na
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- Details

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

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

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Financial instruments (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair value disclosure
Repayment of debt		$ 120,518	$ 69,180	$ 115,540
Carrying Value
Fair value disclosure
Financial instruments		207,805	248,340
Fair Value \| Level 2
Fair value disclosure
Financial instruments		204,458	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		189,134	178,938
Notes payable \| Fair Value \| Level 2
Fair value disclosure
Financial instruments		187,675	177,149
New England Pension Fund withdrawal liability
Fair value disclosure
Outstanding withdrawal liability		18,700
New England Pension Fund withdrawal liability \| Accrued expenses
Fair value disclosure
Outstanding withdrawal liability		800
New England Pension Fund withdrawal liability \| Carrying Value
Fair value disclosure
Financial instruments		18,671	19,402
New England Pension Fund withdrawal liability \| Fair Value \| Level 2
Fair value disclosure
Financial instruments		$ 16,783	$ 18,220
Measurement input		0.06	0.053
Financial Instrument, Measurement Input		us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember