UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net Income	$ 38,218	$ 19,876
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	38,251	25,288
Deferred taxes	11,767	7,713
Compensation expense related to share-based compensation plans	6,982	4,972
Contingent consideration adjustment	(3,571)
(Gain) loss on sale of assets	(90)	307
Changes in operating assets and liabilities:
Restricted investments	74	(2,408)
Accounts receivable, net	(29,748)	26,240
Prepaid taxes	6,820	(3,352)
Prepaid expenses and other current assets	9,935	4,493
Other assets	1,869	(2,653)
Accounts payable	9,878	307
Accrued expenses	4,857	(18,013)
Non-current liabilities	2,382	368
Net cash provided by operating activities	97,624	63,138
Cash flows from investing activities:
Proceeds from sale of equipment	1,234	2,356
Purchases of property and equipment	(69,261)	(29,593)
Net cash used in investing activities	(68,027)	(27,237)
Cash flows from financing activities:
Proceeds from issuance of debt	58,161	16,149
Repayments of long term debt	(84,051)	(23,118)
Stock tendered for payments of withholding taxes	(4,017)	(3,293)
Capital lease payments	(1,483)	(1,399)
Net cash used in financing activities	(31,390)	(11,661)
Effect of exchange rate changes on cash and cash equivalents	(11)	95
Net (decrease) increase in cash and cash equivalents	(1,804)	24,335
Cash and cash equivalents beginning of the period	28,557	127,404
Cash and cash equivalents end of the period	26,753	151,739
Supplemental disclosures of cash paid for:
Interest	4,182	2,176
Income taxes	$ 752	$ 10,743