UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net Income	$ 10,276us-gaap_NetIncomeLoss	$ 12,035us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,731	6,779
Deferred taxes	1,593	1,991
Compensation expense related to share-based compensation plans	2,034us-gaap_ShareBasedCompensation	2,143us-gaap_ShareBasedCompensation
Gain on sale of assets		(6)
Excess tax benefits from share based compensation	(13)
Changes in operating assets and liabilities:
Restricted investments	98	(117)
Accounts receivable, net	2,874us-gaap_IncreaseDecreaseInReceivables	(31,471)us-gaap_IncreaseDecreaseInReceivables
Prepaid taxes	4,557us-gaap_IncreaseDecreaseInPrepaidTaxes	86us-gaap_IncreaseDecreaseInPrepaidTaxes
Prepaid expenses and other current assets	(3,246)	(597)
Other assets	330	(837)
Accounts payable	13,414	29,286
Accrued expenses	5,733	1,128
Non-current liabilities	(1,052)	(1,839)
Net cash provided by operating activities	45,329	18,581
Cash flows from investing activities:
Proceeds from sale of equipment	26	85
Purchases of property and equipment	(15,057)	(33,035)
Net cash used in investing activities	(15,031)	(32,950)
Cash flows from financing activities:
Proceeds from issuance of debt	11,480	25,361
Repayments of long term debt	(5,553)us-gaap_RepaymentsOfLongTermDebt	(1,124)us-gaap_RepaymentsOfLongTermDebt
Stock tendered for payments of withholding taxes	(2,754)	(3,023)
Purchase of treasury stock	(13,419)
Capital lease payments	(605)	(616)
Excess tax benefits from share-based compensation	42	104
Net cash (used in) provided by financing activities	(10,809)	20,702
Effect of exchange rate changes on cash and cash equivalents	3
Net increase in cash and cash equivalents	19,492	6,333
Cash and cash equivalents beginning of the year	109,769	68,964
Cash and cash equivalents end of the year	129,261	75,297
Supplemental disclosures of cash paid for:
Interest	789us-gaap_InterestPaid	380us-gaap_InterestPaid
Income taxes	$ 194us-gaap_IncomeTaxesPaid	$ 777us-gaap_IncomeTaxesPaid

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.