Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 7,707	$ 6,377
Trade accounts receivable, net	858,720	745,288
Prepaid expenses and other	140,164	194,016
Total current assets	1,006,591	945,681
Property and equipment, at cost	4,507,917	4,258,915
Less accumulated depreciation	1,632,108	1,440,124
Net property and equipment	2,875,809	2,818,791
Goodwill	55,737
Other intangible assets, net	58,685
Other assets	57,101	64,516
Total assets	4,053,923	3,828,988
Current liabilities:
Trade accounts payable	493,585	384,308
Claims accruals	117,645	109,745
Accrued payroll	47,514	51,929
Other accrued expenses	23,011	27,152
Total current liabilities	681,755	573,134
Long-term debt	1,084,801	986,278
Other long-term liabilities	68,564	64,881
Deferred income taxes	746,833	790,634
Stockholders' equity	1,471,970	1,414,061
Total liabilities and stockholders' equity	$ 4,053,923	$ 3,828,988