Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 496	$ 4,720
Accounts receivable, net	191,437	170,278
Prepaid expenses and other	34,066	28,251
Total current assets	225,999	203,249
Property and Equipment, at cost	1,334,557	1,289,994
Less-accumulated depreciation	573,699	554,214
Net property and equipment	760,858	735,780
Goodwill and Identifiable Intangibles, net	23,686	24,027
Other Noncurrent Assets	5,004	4,259
Total assets	1,015,547	967,315
Current Liabilities:
Accounts payable	65,866	57,438
Wages, vacation and employees’ benefits	38,939	39,748
Claims and insurance accruals	39,049	35,850
Other current liabilities	20,032	19,807
Current portion of long-term debt	14,791	14,083
Total current liabilities	178,677	166,926
Other Liabilities:
Long-term debt, less current portion	127,782	118,833
Deferred income taxes	61,031	59,423
Claims, insurance and other	40,663	39,639
Total other liabilities	229,476	217,895
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, 25,680,415 and 25,551,617 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	26	26
Additional paid-in-capital	250,233	246,454
Deferred compensation trust, 160,379 and 170,310 shares of common stock at cost at March 31, 2018 and December 31, 2017, respectively	(3,490)	(3,486)
Retained earnings	360,625	339,500
Total stockholders’ equity	607,394	582,494
Total liabilities and stockholders’ equity	$ 1,015,547	$ 967,315