LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Details) (USD $)								6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Term Loan	Jun. 30, 2012 Capital lease obligations	Dec. 31, 2011 Capital lease obligations	Jun. 30, 2012 Notes payable	Dec. 31, 2011 Notes payable	Jun. 30, 2012 Notes payable ABF M
Long-term debt obligations
Long-term debt	$ 180,078,000	$ 71,012,000	$ 100,000,000	$ 36,746,000	$ 44,261,000	$ 43,332,000	$ 26,751,000
Less current portion	46,282,000	24,262,000
Long-term debt, less current portion	133,796,000	46,750,000
Interest rate (as a percent)			2.00%
Weighted-average interest rate (as a percent)				4.40%		3.10%
Revenue equipment financed during the period under notes payable agreements								21,400,000
Debt instrument, term (in months or years)								36
Payments under long-term debt obligations
Due in one year or less	51,115,000		12,528,000	21,417,000		17,170,000
Due after one year through two years	43,639,000		14,611,000	11,620,000		17,408,000
Due after two years through three years	29,633,000		16,779,000	2,497,000		10,357,000
Due after three years through four years	21,559,000		18,888,000	2,433,000		238,000
Due after four years through five years	46,135,000		45,919,000	216,000
Due after five years	587,000			587,000
Total payments	192,668,000		108,725,000	38,770,000		45,173,000
Less amounts representing interest	12,590,000		8,725,000	2,024,000		1,841,000
Long-term debt	$ 180,078,000	$ 71,012,000	$ 100,000,000	$ 36,746,000	$ 44,261,000	$ 43,332,000	$ 26,751,000