PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Details) (USD $)	1 Months Ended	6 Months Ended		3 Months Ended			6 Months Ended		12 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Apr. 30, 2008 ABF Y	Jun. 30, 2012 ABF plan	Jan. 02, 2011 ABF	Jun. 30, 2012 Nonunion Defined Benefit Pension Plan	Mar. 31, 2012 Nonunion Defined Benefit Pension Plan	Jun. 30, 2011 Nonunion Defined Benefit Pension Plan	Jun. 30, 2012 Nonunion Defined Benefit Pension Plan	Jun. 30, 2011 Nonunion Defined Benefit Pension Plan	Dec. 31, 2011 Nonunion Defined Benefit Pension Plan	Jan. 02, 2012 Nonunion Defined Benefit Pension Plan	Jun. 30, 2012 Supplemental Benefit Pension Plan	Jun. 30, 2011 Supplemental Benefit Pension Plan	Jun. 30, 2012 Supplemental Benefit Pension Plan	Jun. 30, 2011 Supplemental Benefit Pension Plan	Jun. 30, 2012 Postretirement Health Benefit Plan	Jun. 30, 2011 Postretirement Health Benefit Plan	Jun. 30, 2012 Postretirement Health Benefit Plan	Jun. 30, 2011 Postretirement Health Benefit Plan
Components of net periodic benefit cost
Service cost				$ 2,297,000		$ 2,164,000	$ 4,594,000	$ 4,328,000							$ 78,000	$ 56,000	$ 157,000	$ 112,000
Interest cost				2,173,000		2,488,000	4,346,000	4,977,000			53,000	96,000	105,000	193,000	188,000	196,000	375,000	391,000
Expected return on plan assets				(3,016,000)		(3,146,000)	(6,032,000)	(6,292,000)
Amortization of prior service credit															(47,000)	(47,000)	(95,000)	(95,000)
Amortization of net actuarial loss and other				2,692,000		1,730,000	5,384,000	3,460,000			50,000	82,000	101,000	164,000	104,000	28,000	208,000	56,000
Net periodic benefit cost				4,146,000		3,236,000	8,292,000	6,473,000	12,900,000		103,000	178,000	206,000	357,000	323,000	233,000	645,000	464,000
Employer contributions				15,000,000	3,000,000
Funding target attainment percentage										80.00%
Estimated nonunion defined benefit pension plan expense for the current fiscal year				$ 16,600,000
Multiemployer Plans
Period of collective bargaining agreement (in years)	5
Number of multiemployer pension plans to which ABF currently contributes		25
Maximum required increase in employer's contribution to multiemployer plans that enter reorganization status (as a percent)		7.00%
Proportion of multiemployer pension plan contributions made to Central States Pension Fund (as a percent)		50.00%
Central States Pension Fund actuarially certified funded percentage			58.90%