Amount of pre-tax expenses associated with multiemployer pension fund withdrawal liability.

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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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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- 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

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- 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

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- 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

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

- Definition

Amount of contributions made to multiemployer plan by employer related to pension fund withdrawal liability.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- 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

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- 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

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Period Type:	instant

- 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

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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

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- 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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- 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

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- 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

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- 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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- 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

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Amount of cash outflow for initial lumpsum payment of withdrawal liability from multiemployer plan.

+ References

No definition available.

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- Definition

The aggregate present value of the monthly payments for the multiemployer plan withdrawal liability.

+ References

No definition available.

+ Details

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- 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.

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- 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

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- Definition

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

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Amount of contributions made to multiemployer plan by employer.

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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.

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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%