Condensed Consolidated Balance Sheets (Current Period Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 5,859	$ 5,831
Trade accounts receivable, net	671,298	568,519
Prepaid expenses and other	60,521	105,853
Total current assets	737,678	680,203
Property and equipment, at cost	3,584,953	3,259,814
Less accumulated depreciation	1,199,847	1,147,610
Net property and equipment	2,385,106	2,112,204
Other assets	36,134	26,997
Total assets	3,158,918	2,819,404
Current liabilities:
Current portion of long-term debt	250,000	250,000
Trade accounts payable	352,645	305,465
Claims accruals	87,413	68,221
Accrued payroll	74,862	72,063
Other accrued expenses	11,585	14,062
Deferred income taxes	13,787	2,485
Total current liabilities	790,292	712,296
Long-term debt	587,074	458,417
Other long-term liabilities	65,384	58,274
Deferred income taxes	556,349	577,965
Stockholders' equity	1,159,819	1,012,452
Total liabilities and stockholders' equity	$ 3,158,918	$ 2,819,404