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EMPLOYEE BENEFIT PLANS (Multiemployer Plans) (Details) - Freight Transportation (ABF Freight) $ in Thousands |  |  |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Aug. 01, 2015 | Aug. 01, 2014 | Aug. 01, 2013 | Dec. 31, 2015 USD ($) $ / h plan | Jan. 31, 2015 | Dec. 31, 2014 USD ($) | Jan. 31, 2014 | Dec. 31, 2013 USD ($) | Dec. 31, 2005 | Jan. 01, 2015 | Jan. 01, 2014 | Jan. 01, 2013
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Maximum increase in combined contribution rates for health, welfare, and pension benefits each August 1 | $ / h |  |  |  | 1.00 |  |  |  |  |  |  |  |
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 status |  |  |  | 64.00% |  |  |  |  |  |  |  |
Percentage of contributions to the multiemployer pension plans that are in endangered status |  |  |  | 3.00% |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  | $ 151,898 |  | $ 144,177 |  | $ 136,233 |  |  |  |
Percentage increase in contribution rate for time worked related to benefit costs | 0.020 | 0.020 | 0.020 |  |  |  |  |  |  |  |  |
Multiemployer pension plans | Central States Pension Plan |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  | $ 77,491 |  | $ 74,001 |  | $ 70,020 |  |  |  |
Threshold percentage of the entity's contributions relative to total fund contributions, which was exceeded during the period |  |  |  |  |  | 5.00% |  | 5.00% |  |  |  |
Actuarially certified funded percentage of multiemployer pension plan |  |  |  |  |  |  |  |  |  | 47.90% | 48.40% | 47.60%
Period of extension granted by Internal Revenue Service for amortization of unfunded liabilities |  |  |  |  |  |  |  |  | 10 years |  |  |
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 | Central States Pension Plan | Minimum |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Percentage of contributions to multiemployer pension plan |  |  |  | 50.00% |  | 50.00% |  | 50.00% |  |  |  |
Multiemployer pension plans | Western Conference of Teamsters Pension Plan |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  | $ 24,474 |  | $ 23,030 |  | $ 20,601 |  |  |  |
Multiemployer pension plans | Central Pennsylvania Teamsters Pension Plan |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  | 13,147 |  | 12,810 |  | 12,143 |  |  |  |
Multiemployer pension plans | Local 710 Pension Fund |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  | 10,020 |  | 9,186 |  | 10,001 |  |  |  |
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 |  |  |  | $ 26,766 |  | 25,150 |  | 23,468 |  |  |  |
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 |  |  |  | 43 |  |  |  |  |  |  |  |
Total contributions to multiemployer plans |  |  |  | $ 144,700 |  | $ 130,500 |  | $ 118,000 |  |  |  |
Percentage increase in contribution rate for time worked related to benefit costs | 0.054 | 0.054 | 0.076 |  |  |  |  |  |  |  |  |
Unionized employees concentration risk | Number of employees |  |  |  |  |  |  |  |  |  |  |  |
Multiemployer Plans |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ABF Freight's employees covered under collective bargaining agreement with the IBT |  |  |  | 77.00% |  |  |  |  |  |  |  |

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