OPERATING SEGMENT DATA - (Rev and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
REVENUES
Revenues	$ 651,088	$ 621,455
OPERATING EXPENSES
Salaries, wages, and benefits	334,829	331,137
Fuel, supplies, and expenses	72,662	63,135
Depreciation and amortization	25,394	25,151
Gain on sale of property and equipment	(613)	(311)
Pension settlement expense	1,957	900
Other	28,954	26,598
Restructuring costs	1,631
Total consolidated operating expenses	663,341	630,720
OPERATING INCOME
OPERATING LOSS	(12,253)	(9,265)
OTHER INCOME (COSTS)
Interest and dividend income	274	401
Interest and other related financing costs	(1,315)	(1,247)
Other, net	647	366
TOTAL OTHER INCOME (COSTS)	(394)	(480)
LOSS BEFORE INCOME TAXES	(12,647)	(9,745)
Operating Segments | Asset-Based
REVENUES
Revenues	464,356	439,063
OPERATING EXPENSES
Salaries, wages, and benefits	304,843	296,162
Fuel, supplies, and expenses	75,432	66,689
Operating taxes and licenses	11,869	11,980
Insurance	7,109	6,466
Communications and utilities	4,822	4,372
Depreciation and amortization	20,983	20,392
Rents and purchased transportation	46,608	39,696
Gain on sale of property and equipment	(617)	(172)
Pension settlement expense	1,401	677
Other	1,791	1,800
Restructuring costs	140
Total consolidated operating expenses	474,381	448,062
OPERATING INCOME
OPERATING LOSS	(10,025)	(8,999)
Operating Segments | ArcBest
REVENUES
Revenues	152,876	142,397
OPERATING EXPENSES
Purchased transportation	121,919	111,831
Salaries, wages, and benefits	16,536	18,581
Supplies and expenses	5,286	4,418
Depreciation and amortization	3,366	3,465
Other	4,058	4,094
Restructuring costs	810
Total consolidated operating expenses	151,975	142,389
OPERATING INCOME
OPERATING LOSS	901	8
Operating Segments | FleetNet
REVENUES
Revenues	40,238	43,564
OPERATING EXPENSES
Total consolidated operating expenses	39,264	42,580
OPERATING INCOME
OPERATING LOSS	974	984
Other and eliminations
REVENUES
Revenues	(6,382)	(3,569)
OPERATING EXPENSES
Restructuring costs	(700)
Total consolidated operating expenses	(2,279)	(2,311)
OPERATING INCOME
OPERATING LOSS	$ (4,103)	$ (1,258)