Condensed Consolidated Balance Sheets (Current Period Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 5,646	$ 5,961
Trade accounts receivable, net	631,172	653,795
Prepaid expenses and other	148,063	201,743
Deferred income taxes	18,631	18,631
Total current assets	803,512	880,130
Property and equipment, at cost	3,801,192	3,719,757
Less accumulated depreciation	1,248,329	1,237,225
Net property and equipment	2,552,863	2,482,532
Other assets	72,622	34,455
Total assets	3,428,997	3,397,117
Current liabilities:
Current portion of long-term debt	250,000	250,000
Trade accounts payable	328,111	325,838
Claims accruals	99,196	96,719
Accrued payroll	72,106	80,547
Other accrued expenses	12,918	17,966
Total current liabilities	762,331	771,070
Long-term debt	628,203	683,539
Other long-term liabilities	60,565	59,561
Deferred income taxes	700,518	678,424
Stockholders' equity	1,277,380	1,204,523
Total liabilities and stockholders' equity	$ 3,428,997	$ 3,397,117