Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue:
Freight revenue	$ 136,907	$ 134,220	$ 266,047	$ 256,120
Fuel surcharge revenue	35,581	37,081	71,172	72,212
Total revenue	172,488	171,301	337,219	328,332
Operating expenses:
Salaries, wages, and related expenses	54,800	53,396	109,874	105,558
Fuel expense	46,559	48,217	95,194	96,572
Operations and maintenance	12,351	11,256	24,029	21,667
Revenue equipment rentals and purchased transportation	26,776	22,000	49,461	39,178
Operating taxes and licenses	2,662	3,037	5,435	5,434
Insurance and claims	7,621	6,133	16,115	15,989
Communications and utilities	1,252	1,176	2,536	2,375
General supplies and expenses	4,393	3,846	8,300	7,598
Depreciation and amortization, including gains and losses on disposition of property and equipment	9,724	11,181	20,640	20,545
Total operating expenses	166,138	160,242	331,584	314,916
Operating income	6,350	11,059	5,635	13,416
Other (income) expenses:
Interest expense	2,617	3,355	5,250	6,873
Interest income	(2)		(1)
Other (income) expense, net		(5)		(15)
Other expenses, net	2,615	3,350	5,249	6,858
Equity in income of affiliate	550	425	1,030	670
Income before income taxes	4,285	8,134	1,416	7,228
Income tax expense	2,394	3,883	1,484	3,617
Net income (loss)	$ 1,891	$ 4,251	$ (68)	$ 3,611
Income (loss) per share:
Basic net income (loss) per share (in Dollars per share)	$ 0.13	$ 0.29	$ 0.00	$ 0.25
Diluted net income (loss) per share (in Dollars per share)	$ 0.13	$ 0.29	$ 0.00	$ 0.24
Basic weighted average shares outstanding (in Shares)	14,852	14,732	14,809	14,727
Diluted weighted average shares outstanding (in Shares)	15,052	14,787	14,809	14,796