PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) plan	Jun. 30, 2015 USD ($)	Mar. 31, 2016	Jan. 01, 2016	Dec. 31, 2015
Components of net periodic benefit cost
Pension settlement expense	$ 600	$ 600	$ 1,464	$ 1,716
Pension settlement expense, net of tax	345	364	895	1,048
Freight Transportation (ABF Freight)
Components of net periodic benefit cost
Pension settlement expense	400	400	$ 1,100	1,300
Multiemployer pension plans | Freight Transportation (ABF Freight)
Multiemployer Plans
Number of multiemployer plans to which ABF Freight currently contributes | plan			25
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%
Multiemployer pension plans | Central States Pension Plan
Multiemployer Plans
Maximum projected time to insolvency without legislative action			10 years
Multiemployer pension plans | Central States Pension Plan | Freight Transportation (ABF Freight)
Multiemployer Plans
Approximate proportion of multiemployer pension plan contributions (as a percent)			50.00%
Actuarially certified funded percentage of multiemployer pension plan						46.90%
Multiemployer pension plans | 707 Pension Fund | Freight Transportation (ABF Freight)
Multiemployer Plans
Approximate proportion of multiemployer pension plan contributions (as a percent)			1.00%
Nonunion Defined Benefit Pension Plan
Components of net periodic benefit cost
Interest cost	1,158	1,223	$ 2,463	2,543
Expected return on plan assets	(2,158)	(2,359)	(4,104)	(4,761)
Pension settlement expense	564	597	1,464	1,716
Amortization of net actuarial loss	1,061	815	2,017	1,636
Net periodic benefit cost	625	276	1,840	1,134
Pension settlement expense, net of tax	300	400	900	1,000
Lump-sum distributions	2,700	4,800	7,200	12,400
Change in projected benefit obligation
Benefit obligations at beginning of period			159,607
Interest cost	1,158	1,223	2,463	2,543
Actuarial loss			9,377
Benefits paid			(7,420)
Benefit obligations at end of period	164,027		164,027
Change in plan assets
Fair value of plan assets at beginning of period			136,917
Actual return on plan assets			4,587
Employer contributions			13,400
Benefits paid			(7,420)
Fair value of plan assets at end of period	147,484		147,484
Funded status	(16,543)		(16,543)
Accumulated benefit obligation	$ 164,027		$ 164,027
Discount rate (as a percent)	2.70%		2.70%		3.00%		3.50%
Adjusted funding target attainment percentage						109.20%
Supplemental Benefit Plan
Components of net periodic benefit cost
Interest cost	$ 33	30	$ 65	61
Amortization of net actuarial loss	38	40	76	80
Net periodic benefit cost	71	70	141	141
Change in projected benefit obligation
Interest cost	33	30	65	61
Postretirement Health Benefit Plan
Components of net periodic benefit cost
Service cost	107	102	214	203
Interest cost	255	229	509	457
Amortization of prior service credit	(48)	(48)	(95)	(95)
Amortization of net actuarial loss	176	213	352	426
Net periodic benefit cost	490	496	980	991
Change in projected benefit obligation
Interest cost	$ 255	$ 229	$ 509	$ 457