Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue:
Freight revenue	$ 137,678	$ 135,991	$ 263,951	$ 264,165
Fuel surcharge revenue	35,976	36,497	70,660	73,054
Total revenue	173,654	172,488	334,611	337,219
Operating expenses:
Salaries, wages, and related expenses	56,141	54,800	109,015	109,874
Fuel expense	41,915	46,559	85,091	95,194
Operations and maintenance	11,533	12,522	23,564	24,383
Revenue equipment rentals and purchased transportation	27,612	26,776	52,946	49,461
Operating taxes and licenses	2,562	2,662	5,308	5,435
Insurance and claims	7,578	7,450	13,684	15,761
Communications and utilities	1,427	1,252	2,864	2,536
General supplies and expenses	4,529	4,393	8,338	8,300
Depreciation and amortization, including gains and losses on disposition of property and equipment	11,301	9,724	24,391	20,640
Total operating expenses	164,598	166,138	325,201	331,584
Operating income	9,056	6,350	9,410	5,635
Other (income) expenses:
Interest expense	2,722	2,617	5,473	5,250
Interest income	(4)	(2)	(8)	(1)
Other expenses, net	2,718	2,615	5,465	5,249
Equity in income of affiliate	850	550	1,650	1,030
Income before income taxes	7,188	4,285	5,595	1,416
Income tax expense	3,408	2,394	3,189	1,484
Net income (loss)	$ 3,780	$ 1,891	$ 2,406	$ (68)
Income (loss) per share:
Basic net income (loss) per share (in Dollars per share)	$ 0.25	$ 0.13	$ 0.16	$ 0.00
Diluted net income (loss) per share (in Dollars per share)	$ 0.25	$ 0.13	$ 0.16	$ 0.00
Basic weighted average shares outstanding (in Shares)	14,930	14,852	14,922	14,809
Diluted weighted average shares outstanding (in Shares)	15,179	15,052	15,176	14,809