Condensed Consolidated Balance Sheets (Current Period Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 5,870	$ 5,831
Trade accounts receivable, net	667,620	568,519
Prepaid expenses and other	65,735	105,853
Total current assets	739,225	680,203
Property and equipment, at cost	3,488,606	3,259,814
Less accumulated depreciation	1,172,061	1,147,610
Net property and equipment	2,316,545	2,112,204
Other assets	35,589	26,997
Total assets	3,091,359	2,819,404
Current liabilities:
Current portion of long-term debt		250,000
Trade accounts payable	338,063	305,465
Claims accruals	81,221	68,221
Accrued payroll	75,170	72,063
Other accrued expenses	17,695	14,062
Deferred income taxes	2,485	2,485
Total current liabilities	514,634	712,296
Long-term debt	874,028	458,417
Other long-term liabilities	61,287	58,274
Deferred income taxes	560,293	577,965
Stockholders' equity	1,081,117	1,012,452
Total liabilities and stockholders' equity	$ 3,091,359	$ 2,819,404