Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net income (loss)	$ (42,394)	$ 11,141	$ 17,632
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Deferred income tax provision (benefit)	(15,752)	(861)	4,470
Depreciation and amortization	82,756	82,975	90,116
(Gains) losses on sale of equipment	(467)	(999)	12,711
Share based compensation	5,287	6,244	4,395
Other	(332)	(684)	(3,367)
Unrealized loss (gain) on equity investment	12,096	(7,677)
Changes in operating assets and liabilities:
Receivables	6,839	(38,556)	(10,048)
Prepaid insurance and licenses	99	398	(2,939)
Operating supplies	1,234	(465)	(900)
Other assets	(149)	(20,578)	(3,718)
Accounts payable and other accrued liabilities	3,136	41,345	19,940
Accrued wages and benefits	(9,553)	4,916	15,863
Net cash provided by operating activities	43,464	78,567	150,889
Investing activities
Payments for purchases of property and equipment	(199,134)	(192,366)	(186,122)
Proceeds from sales of property and equipment	46,020	95,369	81,399
Other			(6,880)
Net cash used in investing activities	(153,114)	(96,997)	(111,603)
Financing activities
Borrowings under lines of credit	494,196	334,512	278,654
Payments under lines of credit	(421,896)	(310,612)	(278,654)
Borrowings under long-term debt	130,336	124,721	263,992
Payments of long-term debt and finance leases	(95,054)	(137,661)	(301,059)
Payments of financing costs		(100)	(1,391)
Payments of long-term consideration for business acquisition			(1,000)
Tax withholding related to net share settlement of restricted stock awards	(440)	(1,237)	(135)
Proceeds from issuance of common stock under ESPP	1,323	1,284	851
Proceeds from long-term consideration for sale of subsidiary	648	617	587
Book overdraft	(2,883)	7,096	(1,313)
Net cash provided by (used in) financing activities	106,230	18,620	(39,468)
Net change in cash and cash equivalents	(3,420)	190	(182)
Cash and cash equivalents
Beginning of year	5,695	5,505	5,687
End of period	2,275	5,695	5,505
Supplemental disclosure of cash flow information
Cash paid during the year for interest	17,572	13,916	17,620
Cash paid during the year for income taxes	1,601	995	705
Supplemental disclosure of significant noncash investing and financing activities
Property and equipment amounts accrued in accounts payable	5,777	1,656	867
Finance lease additions	$ 1,117	5,572
Uncollected proceeds from asset sales		$ 2,581	406
Subsidiary stock issued in business combination			$ 7,278