OPERATING SEGMENT DATA (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
REVENUES
Revenues	$ 676,627	$ 696,115	$ 1,298,082	$ 1,309,391
OPERATING EXPENSES
Salaries, wages, and benefits	335,094	332,510	664,563	639,426
Rents, purchased transportation, and other costs of services	199,352	200,619	382,440	378,585
Fuel, supplies, and expenses	70,406	78,127	134,626	154,029
Depreciation and amortization	25,748	22,616	50,899	44,848
Gain on sale of property and equipment			(2,486)	(1,049)
Pension settlement expense	600	600	1,464	1,716
Other	29,373	28,777	58,165	57,757
Total consolidated operating expenses	659,973	662,649	1,290,693	1,274,645
OPERATING INCOME
OPERATING INCOME	16,654	33,466	7,389	34,746
OTHER INCOME (COSTS)
Interest and dividend income	387	271	788	505
Interest and other related financing costs	(1,231)	(1,025)	(2,478)	(2,027)
Other, net	571	197	937	597
TOTAL OTHER INCOME (COSTS)	(273)	(557)	(753)	(925)
INCOME BEFORE INCOME TAXES	16,381	32,909	6,636	33,821
Freight Transportation (ABF Freight)
OPERATING EXPENSES
Pension settlement expense	400	400	1,100	1,300
Operating Segments | Freight Transportation (ABF Freight)
REVENUES
Revenues	486,731	504,371	926,239	945,578
OPERATING EXPENSES
Salaries, wages, and benefits	303,693	301,639	600,300	580,010
Fuel, supplies, and expenses	72,279	79,647	138,968	158,673
Operating taxes and licenses	12,154	12,322	24,134	24,318
Insurance	7,660	6,267	14,126	12,052
Communications and utilities	4,279	3,766	8,651	7,751
Depreciation and amortization	20,911	18,286	41,303	35,686
Rents and purchased transportation	47,800	52,380	87,496	94,224
Gain on sale of property and equipment	(2,197)	(594)	(2,369)	(838)
Pension settlement expense	424	448	1,101	1,288
Other	2,356	2,118	4,156	4,279
Total consolidated operating expenses	469,359	476,279	917,866	917,443
OPERATING INCOME
OPERATING INCOME	17,372	28,092	8,373	28,135
Operating Segments | Premium Logistics (Panther)
REVENUES
Revenues	69,705	80,271	135,783	155,563
OPERATING EXPENSES
Purchased transportation	52,007	58,510	100,858	114,554
Depreciation and amortization	2,868	2,939	5,705	5,863
Salaries, benefits, insurance, and other	13,728	13,984	27,862	29,113
Total consolidated operating expenses	68,603	75,433	134,425	149,530
OPERATING INCOME
OPERATING INCOME	1,102	4,838	1,358	6,033
Operating Segments | Transportation Management (ABF Logistics)
REVENUES
Revenues	67,955	50,419	134,902	97,791
OPERATING EXPENSES
Total consolidated operating expenses	67,459	48,611	133,740	95,208
OPERATING INCOME
OPERATING INCOME	496	1,808	1,162	2,583
Operating Segments | Emergency & Preventative Maintenance (FleetNet)
REVENUES
Revenues	41,780	42,015	85,344	84,504
OPERATING EXPENSES
Total consolidated operating expenses	41,184	40,998	83,764	82,317
OPERATING INCOME
OPERATING INCOME	596	1,017	1,580	2,187
Operating Segments | Household Goods Moving Services (ABF Moving)
REVENUES
Revenues	25,742	32,225	43,886	50,793
OPERATING EXPENSES
Total consolidated operating expenses	24,872	30,228	43,765	49,159
OPERATING INCOME
OPERATING INCOME	870	1,997	121	1,634
Operating Segments | Asset-Light Logistics Segments | Maximum
OPERATING EXPENSES
Pension settlement expense	100	100	100	100
Other and eliminations
REVENUES
Revenues	(15,286)	(13,186)	(28,072)	(24,838)
OPERATING EXPENSES
Pension settlement expense	100	100	300	300
Total consolidated operating expenses	(11,504)	(8,900)	(22,867)	(19,012)
OPERATING INCOME
OPERATING INCOME	$ (3,782)	$ (4,286)	$ (5,205)	$ (5,826)