Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 711	$ 1,539
Accounts receivable, net	148,968	135,083
Prepaid expenses and other	34,969	29,857
Total current assets	184,648	166,479
Property and Equipment, at cost	1,216,711	1,101,946
Less-accumulated depreciation	504,324	497,827
Net property and equipment	712,387	604,119
Goodwill and Identifiable Intangibles, net	25,054	25,398
Other Noncurrent Assets	5,107	4,374
Total assets	927,196	800,370
Current Liabilities:
Accounts payable	70,971	45,149
Wages, vacation and employees’ benefits	33,098	31,700
Other current liabilities	51,103	51,333
Current portion of long-term debt	19,183	16,762
Total current liabilities	174,355	144,944
Other Liabilities:
Long-term debt, less current portion	137,738	57,042
Deferred income taxes	82,738	80,199
Claims, insurance and other	36,898	35,107
Total other liabilities	257,374	172,348
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, 25,446,515 and 25,141,799 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	25	25
Additional paid-in-capital	238,995	237,846
Deferred compensation trust, 169,907 and 165,971 shares of common stock at cost at March 31, 2017 and December 31, 2016, respectively	(3,337)	(3,190)
Retained earnings	259,784	248,397
Total stockholders’ equity	495,467	483,078
Total liabilities and stockholders’ equity	$ 927,196	$ 800,370