OPERATING SEGMENT DATA - (Rev and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
REVENUES
Revenues	$ 720,368	$ 676,627	$ 1,371,456	$ 1,298,082
OPERATING EXPENSES
Salaries, wages, and benefits	350,187	336,670	685,016	667,807
Fuel, supplies, and expenses	68,451	69,361	141,113	132,496
Depreciation and amortization	25,209	25,748	50,603	50,899
(Gain) loss on sale of property and equipment			(412)	(2,486)
Pension settlement expense	700	600	2,701	1,464
Other	35,187	27,246	64,141	53,844
Restructuring costs	363		1,994
Total consolidated operating expenses	695,634	659,973	1,358,975	1,290,693
OPERATING INCOME
OPERATING INCOME	24,734	16,654	12,481	7,389
OTHER INCOME (COSTS)
Interest and dividend income	285	387	559	788
Interest and other related financing costs	(1,389)	(1,231)	(2,704)	(2,478)
Other, net	505	571	1,152	937
TOTAL OTHER COSTS	(599)	(273)	(993)	(753)
INCOME BEFORE INCOME TAXES	24,135	16,381	11,488	6,636
Operating Segments | Asset-Based
REVENUES
Revenues	514,537	486,251	978,893	925,314
OPERATING EXPENSES
Salaries, wages, and benefits	314,252	303,214	619,095	599,376
Fuel, supplies, and expenses	75,878	72,279	151,310	138,968
Operating taxes and licenses	12,252	12,154	24,121	24,134
Insurance	7,540	7,660	14,649	14,126
Communications and utilities	4,535	4,279	9,357	8,651
Depreciation and amortization	21,324	20,911	42,307	41,303
Rents and purchased transportation	53,346	47,800	99,954	87,496
(Gain) loss on sale of property and equipment	25	(2,197)	(592)	(2,369)
Pension settlement expense	533	424	1,934	1,101
Other	2,658	2,355	4,449	4,155
Restructuring costs	33		173
Total consolidated operating expenses	492,376	468,879	966,757	916,941
OPERATING INCOME
OPERATING INCOME	22,161	17,372	12,136	8,373
Operating Segments | ArcBest
REVENUES
Revenues	175,929	154,347	328,805	296,744
OPERATING EXPENSES
Purchased transportation	139,354	121,502	261,273	233,333
Salaries, wages, and benefits	16,762	17,668	33,298	36,249
Supplies and expenses	6,769	4,641	12,055	9,059
Depreciation and amortization	3,337	3,475	6,703	6,940
Other	3,828	4,888	7,886	8,982
Restructuring costs	65		875
Total consolidated operating expenses	170,115	152,174	322,090	294,563
OPERATING INCOME
OPERATING INCOME	5,814	2,173	6,715	2,181
Operating Segments | FleetNet
REVENUES
Revenues	36,501	41,780	76,739	85,344
OPERATING EXPENSES
Total consolidated operating expenses	35,771	41,184	75,035	83,764
OPERATING INCOME
OPERATING INCOME	730	596	1,704	1,580
Other and eliminations
REVENUES
Revenues	(6,599)	(5,751)	(12,981)	(9,320)
OPERATING EXPENSES
Restructuring costs	300		900
Total consolidated operating expenses	(2,628)	(2,264)	(4,907)	(4,575)
OPERATING INCOME
OPERATING INCOME	$ (3,971)	$ (3,487)	$ (8,074)	$ (4,745)