Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 26,559	$ (24,556)
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Provision for losses on accounts receivable	833	3,355
Reversal (deferral) of gain on sales to equity method investee	53	(2)
Depreciation and amortization	27,951	37,853
Impairment of property and equipment	0	26,569
Amortization of deferred financing fees	0	73
Deferred income tax expense (benefit)	7,274	(9,139)
Income tax (expense) benefit arising from restricted share vesting and stock options exercised	(255)	17
Stock-based compensation expense	4,946	822
(Income) loss from equity method investment	(6,342)	205
Return on investment in affiliated company	0	0
Gain on disposition of property and equipment	(2,812)	(4,946)
Gain on reversal of contingent loss of discontinued operations	(3,412)	0
Gain on investment in available-for-sale securities	(63)	(2)
Changes in operating assets and liabilities:
Receivables and advances	(44,671)	(34,802)
Prepaid expenses and other assets	547	2,093
Inventory and supplies	(436)	639
Insurance and claims accrual	7,854	18,751
Accounts payable and accrued expenses	16,097	7,172
Net cash flows provided by operating activities	34,123	24,102
Cash flows from investing activities:
Other investment	(13)	0
Purchase of available-for-sale securities	(33)	(405)
Acquisition of property and equipment	(13,971)	(46,991)
Proceeds from disposition of property and equipment	33,797	51,479
Net cash flows provided by investing activities	19,780	4,083
Cash flows from financing activities:
Change in checks outstanding in excess of bank balances	(1,215)	21
Proceeds from issuance of notes payable	0	55,345
Repayments of notes payable	(9,383)	(39,859)
Repayments of finance lease obligations	(1,481)	(2,661)
Proceeds under revolving credit facility	446,978	803,397
Repayments under revolving credit facility and draw note	(482,996)	(803,397)
Payment of minimum tax withholdings on stock compensation	(887)	(9)
Common stock repurchased	(8,360)	(17,486)
Net cash flows used by financing activities	(57,344)	(4,649)
Net change in cash and cash equivalents	(3,441)	23,536
Cash and cash equivalents at beginning of period	8,407	43,591
Cash and cash equivalents at end of period	$ 4,966	$ 67,127