PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010
Nonunion Defined Benefit Pension Plan
Components of net periodic benefit cost
Service cost	$ 2,164	$ 2,236	$ 4,328	$ 4,472
Interest cost	2,488	2,734	4,977	5,468
Expected return on plan assets	(3,146)	(3,043)	(6,292)	(6,086)
Amortization of prior service credit		(1)		(3)
Amortization of net actuarial loss and other	1,730	1,896	3,460	3,794
Net periodic benefit cost	3,236	3,822	6,473	7,645
Estimated nonunion defined benefit pension plan expense for the current fiscal year					12,900	15,300
Supplemental Benefit Pension Plan
Components of net periodic benefit cost
Interest cost	96	103	193	208
Pension settlement expense		178		178
Amortization of net actuarial loss and other	82	70	164	129
Net periodic benefit cost	178	351	357	515
Postretirement Health Benefit Plan
Components of net periodic benefit cost
Service cost	56	35	112	70
Interest cost	196	217	391	435
Amortization of transition obligation		33		67
Amortization of prior service credit	(47)		(95)
Amortization of net actuarial loss and other	28	5	56	9
Net periodic benefit cost	$ 233	$ 290	$ 464	$ 581
ABF
Multiemployer Plans
Number of multiemployer pension plans in which ABF currently contributes			25
Period of collective bargaining agreement (in years)			5
Maximum required increase in employer's contribution to multiemployer plans that enter reorganization status			7.00%