Represents the projected funded percentage of a specified multiemployer pension plan.

No definition available.

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- Definition

Represents the maximum funded percentage of plans in the red zone.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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Period Type:	duration

- Definition

Represents the maximum funded percentage of plans in the yellow zone.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum funded percentage of plans in the yellow zone.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- 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

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Namespace Prefix:	arcb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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
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Data Type:	num:percentItemType
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Period Type:	duration

- 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
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

- 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
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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
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Data Type:	num:percentItemType
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Period Type:	duration

- 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

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Balance Type:	na
Period Type:	duration

- Definition

The maximum annual increase in the employer's combined health, welfare and pension benefit contribution rate for multiemployer plans.

+ References

No definition available.

+ Details

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Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- 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

- 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
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum period within which a plan is expected to become insolvent without legislation action.

+ References

No definition available.

+ Details

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Namespace Prefix:	arcb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of multiemployer plans to which the reporting entity currently contributes.

+ References

No definition available.

+ Details

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Namespace Prefix:	arcb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- 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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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 2: http://www.xbrl.org/2003/role/presentationRef
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-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

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

- References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Increase (decrease) in the employer's contractual contribution rate to the multiemployer plan. A multiemployer plan is 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
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-Paragraph 6
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-Section 50
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-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947

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EMPLOYEE BENEFIT PLANS (Multiemployer Plans) (Details) - Asset-Based $ in Thousands				12 Months Ended
	Aug. 01, 2016	Aug. 01, 2015	Aug. 01, 2014	Dec. 31, 2016 USD ($) $ / h plan	Jan. 31, 2016	Dec. 31, 2015 USD ($)	Jan. 31, 2015	Dec. 31, 2014 USD ($)	Jan. 01, 2016	Jan. 01, 2015	Jan. 01, 2014
Multiemployer Plans
Maximum increase in combined contribution rates for health, welfare, and pension benefits each August 1 \| $ / h				1.00
Minimum funded percentage of plans in green zone				80.00%
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				60.00%
Percentage of contributions to the multiemployer pension plans that are in critical status				4.00%
Percentage of contributions to the multiemployer pension plans that are in endangered status				3.00%
Total contributions to multiemployer plans				$ 154,139		$ 151,898		$ 144,177
Percentage increase in contribution rate for time worked related to benefit costs	0.028	0.013	0.008
Maximum projected time to insolvency without legislative action				10 years
Multiemployer pension plans \| Central States Pension Plan
Multiemployer Plans
Total contributions to multiemployer plans				$ 77,891		$ 77,491		$ 74,001
Threshold percentage of the entity's contributions relative to total fund contributions, which was exceeded during the period						5.00%		5.00%
Actuarially certified projected funded percentage of multiemployer pension plan									42.10%	47.90%	48.40%
Multiemployer pension plans \| Central States Pension Plan \| Minimum
Multiemployer Plans
Percentage of contributions to multiemployer pension plan				50.00%		50.00%		50.00%
Multiemployer pension plans \| Central States Pension Plan \| Maximum
Multiemployer Plans
Percentage of contributions to multiemployer pension plan				60.00%		60.00%		60.00%
Multiemployer pension plans \| Western Conference of Teamsters Pension Plan
Multiemployer Plans
Total contributions to multiemployer plans				$ 25,075		$ 24,474		$ 23,030
Multiemployer pension plans \| Central Pennsylvania Teamsters Pension Plan
Multiemployer Plans
Total contributions to multiemployer plans				13,381		13,147		12,810
Multiemployer pension plans \| Local 710 Pension Fund
Multiemployer Plans
Total contributions to multiemployer plans				9,670		10,020		9,186
Threshold percentage of the entity's contributions relative to total fund contributions, which was exceeded during the period					5.00%		5.00%
Multiemployer pension plans \| All Other Pension Plans in Aggregate
Multiemployer Plans
Total contributions to multiemployer plans				$ 28,122		26,766		25,150
Multiemployer pension plans \| 707 Pension Fund
Multiemployer Plans
Percentage of contributions to multiemployer pension plan				1.00%
Multiemployer health and welfare plans
Multiemployer Plans
Number of multiemployer plans to which ABF Freight currently contributes \| plan				42
Total contributions to multiemployer plans				$ 153,300		$ 144,700		$ 130,500
Percentage increase in contribution rate for time worked related to benefit costs	0.040	0.056	0.053
Unionized employees concentration risk \| Number of employees
Multiemployer Plans
Percentage of Asset-Based segment employees covered under collective bargaining agreement with the IBT				77.00%