Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 10,504	$ 14,388
Adjustments to reconcile net income to net cash provided by operating activities:
(Reversal of losses on) provision for accounts receivable	(32)	113
Reversal of gain on sales to equity method investee	(7)	(171)
Depreciation and amortization	40,426	36,829
Amortization of deferred financing fees	73	73
Deferred income tax expense	3,221	6,495
Income tax benefit arising from restricted share vesting and stock options exercised	668	4
Stock-based compensation expense	(171)	2,138
Income from equity method investment	(5,410)	(3,265)
(Gain) Loss on disposition of property and equipment	(1,386)	684
Return on investment in available-for-sale securities	(7)
Changes in operating assets and liabilities:
Receivables and advances	164	11,821
Prepaid expenses and other assets	(2,971)	(5,238)
Inventory and supplies	(75)	(81)
Insurance and claims accrual	(4,255)	(2,793)
Operating leases	(17)
Accounts payable and accrued expenses	(17,128)	1,635
Net cash flows provided by operating activities	23,597	62,632
Cash flows from investing activities:
Purchase of available-for-sale securities	(1,780)
Acquisition of property and equipment	(79,125)	(31,771)
Proceeds from disposition of property and equipment	15,569	38,127
Net cash flows (used) provided by investing activities	(65,336)	6,356
Cash flows from financing activities:
Change in checks outstanding in excess of bank balances	(247)
Proceeds from issuance of notes payable	57,555	78,832
Repayments of notes payable	(19,733)	(30,455)
Repayments of finance lease obligations	(2,876)	(1,534)
Proceeds under revolving credit facility	843,398	755,886
Repayments under revolving credit facility	(829,995)	(764,892)
Payment of minimum tax withholdings on stock compensation	(667)	(18)
Debt refinancing costs		(17)
Net cash flows provided by financing activities	47,435	37,802
Net change in cash and cash equivalents	5,696	106,790
Cash and cash equivalents at beginning of period	23,127	15,356
Cash and cash equivalents at end of period	$ 28,823	$ 122,146