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INCOME TAXES (Deferred taxes) (Details) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017
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Deferred tax assets: |  |
Valuation allowance | $ 0.6 | $ 0.8
Valuation allowance related to anticipated foreign tax credit carryforward | $ 0.5 |

X
- Definition Amount of valuation allowance to the current tax asset relating to anticipated foreign tax credit carryforward. + References No definition available. + Details
Name: | arcb_DeferredTaxAssetValuationAllowanceForeignTaxCreditCarryforward
Namespace Prefix: | arcb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant