Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 4,060	$ 321
Accounts receivable, net	127,542	106,814
Prepaid expenses and other	37,551	37,028
Total current assets	169,153	144,163
Property and Equipment, at cost	787,677	718,527
Less-accumulated depreciation	365,798	356,823
Net property and equipment	421,879	361,704
Goodwill and Identifiable Intangibles, net	8,943	9,404
Other Noncurrent Assets	5,700	4,417
Total assets	605,675	519,688
Current Liabilities:
Accounts payable	48,974	43,706
Wages, vacation and employees' benefits	35,338	30,842
Other current liabilities	44,286	44,609
Current portion of long-term debt	14,643	22,143
Total current liabilities	143,241	141,300
Other Liabilities:
Long-term debt, less current portion	76,863	38,562
Deferred income taxes	59,514	55,611
Claims, insurance and other	31,215	29,696
Total other liabilities	167,592	123,869
Commitments and Contingencies
Stockholders' Equity:
Preferred stock, $0.001 par value, 50,000 shares authorized, none issued and outstanding
Common stock, $0.001 par value, 50,000,000 shares authorized, 24,424,854 and 24,088,416 shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively	24	24
Additional paid-in-capital	211,762	206,969
Deferred compensation trust, 201,936 and 207,755 shares of common stock at cost at September 30, 2013 and December 31, 2012, respectively	(2,246)	(2,213)
Retained earnings	85,302	49,739
Total stockholders' equity	294,842	254,519
Total liabilities and stockholders' equity	$ 605,675	$ 519,688