PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) plan	Sep. 30, 2015 USD ($)	Jun. 30, 2016	Mar. 31, 2016	Jan. 01, 2016	Dec. 31, 2015
Components of net periodic benefit cost
Pension settlement expense	$ 800	$ 800	$ 2,267	$ 2,478
Pension settlement expense, net of tax	490	466	1,385	1,514
Freight Transportation (ABF Freight)
Components of net periodic benefit cost
Pension settlement expense	600	600	$ 1,700	1,900
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 projected 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	1,057	1,356	$ 3,520	3,899
Expected return on plan assets	(2,242)	(2,297)	(6,346)	(7,058)
Pension settlement expense	803	762	2,267	2,478
Amortization of net actuarial loss	1,106	640	3,123	2,276
Net periodic benefit cost	724	461	2,564	1,595
Pension settlement expense, net of tax	500	500	1,400	1,500
Lump-sum distributions	4,300	4,100	11,600	16,600
Change in projected benefit obligation
Benefit obligations at beginning of period			159,607
Interest cost	1,057	1,356	3,520	3,899
Actuarial loss			10,068
Benefits paid			(11,860)
Benefit obligations at end of period	161,335		161,335
Change in plan assets
Fair value of plan assets at beginning of period			136,917
Actual return on plan assets			9,637
Employer contributions			13,400
Benefits paid			(11,860)
Fair value of plan assets at end of period	148,094		148,094
Funded status	(13,241)		(13,241)
Accumulated benefit obligation	$ 161,335		$ 161,335
Discount rate (as a percent)	2.70%		2.70%		2.70%	3.00%		3.50%
Adjusted funding target attainment percentage							107.80%
Supplemental Benefit Plan
Components of net periodic benefit cost
Interest cost	$ 32	31	$ 97	92
Amortization of net actuarial loss	38	40	114	120
Net periodic benefit cost	70	71	211	212
Change in projected benefit obligation
Interest cost	32	31	97	92
Postretirement Health Benefit Plan
Components of net periodic benefit cost
Service cost	107	101	321	304
Interest cost	254	228	763	685
Amortization of prior service credit	(47)	(47)	(142)	(142)
Amortization of net actuarial loss	177	213	529	639
Net periodic benefit cost	491	495	1,471	1,486
Change in projected benefit obligation
Interest cost	$ 254	$ 228	$ 763	$ 685