Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 21,228	$ 2,406
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for losses on accounts receivable	91	426
Deferred (reversal) gain on sales to equity method investee	75	(72)
Depreciation and amortization	28,973	24,970
Amortization of deferred financing fees	139	123
Deferred income tax benefit	1,815	$ 3,028
Casualty premium credit	(3,600)
Income tax benefit arising from restricted share vesting	(1,757)	$ (145)
Unrealized gain on ineffective portion of fuel hedges	(969)	$ (20)
Return of cash collateral on fuel hedge	5,000
Stock-based compensation expense	800	$ 253
Equity in income of affiliate	(2,720)	(1,650)
Gain on disposition of property and equipment	(297)	(579)
Changes in operating assets and liabilities:
Receivables and advances	16,557	(3,122)
Prepaid expenses and other assets	(1,841)	(933)
Inventory and supplies	86	10
Insurance and claims accrual	(483)	234
Accounts payable and accrued expenses	(6,188)	191
Net cash flows provided by operating activities	56,909	25,120
Cash flows from investing activities:
Acquisition of property and equipment	$ (37,131)	(59,417)
Return on investment in affiliated company		307
Proceeds from disposition of property and equipment	$ 21,620	48,540
Net cash flows used in investing activities	$ (15,511)	(10,570)
Cash flows from financing activities:
Change in checks outstanding in excess of bank balances		(422)
Proceeds from issuance of notes payable	$ 5,098	$ 36,063
Proceeds from the exercise of stock options	1,092
Income tax benefit arising from restricted share vesting	1,757	$ 145
Repayments of notes payable	(44,262)	(48,385)
Repayments of capital lease obligations	$ (857)	(1,468)
Proceeds under revolving credit facility, net		9,813
Payment of minimum tax withholdings on stock compensation	$ (1,786)	(174)
Debt refinancing costs		(34)
Net cash used in financing activities	$ (38,958)	(4,462)
Net change in cash and cash equivalents	2,440	10,088
Cash and cash equivalents at beginning of period	21,330	9,263
Cash and cash equivalents at end of period	$ 23,770	$ 19,351