CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 51,558us-gaap_NetIncomeLoss	$ 69,110us-gaap_NetIncomeLoss	$ 67,953us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	29,380	21,302	21,575
Impairment of software	11,881us-gaap_OtherAssetImpairmentCharges
Impairment of trade name		2,904
Deferred taxes	24,501	16,438	8,786
Compensation expense related to share-based compensation plans	8,258us-gaap_ShareBasedCompensation	7,667us-gaap_ShareBasedCompensation	6,539us-gaap_ShareBasedCompensation
(Gain) loss on sale of assets	(46)	(167)	108
Excess tax benefits from share based compensation		(13)	(29)
Changes in operating assets and liabilities:
Restricted investments	(1,190)	(3,536)	(2,895)
Accounts receivable, net	(28,621)us-gaap_IncreaseDecreaseInReceivables	(25,420)us-gaap_IncreaseDecreaseInReceivables	(22,429)us-gaap_IncreaseDecreaseInReceivables
Prepaid taxes	(14,533)us-gaap_IncreaseDecreaseInPrepaidTaxes	(308)us-gaap_IncreaseDecreaseInPrepaidTaxes	2,253us-gaap_IncreaseDecreaseInPrepaidTaxes
Prepaid expenses and other current assets	(1,621)	(2,137)	(1,562)
Other assets	(2,047)	(682)	459
Accounts payable	20,370	27,635	7,438
Accrued expenses	367	1,736	2,779
Non-current liabilities	284	2,888	1,942
Net cash provided by operating activities	98,541	117,417	92,917
Cash flows from investing activities:
Proceeds from sale of equipment	612	1,837	1,071
Purchases of property and equipment	(119,171)	(110,917)	(56,882)
Cash used in acquisitions, net of cash acquired			(550)
Net cash used in investing activities	(118,559)	(109,080)	(56,361)
Cash flows from financing activities:
Proceeds from issuance of debt	91,084	9,120
Repayments of long term debt	(7,251)us-gaap_RepaymentsOfLongTermDebt	(874)us-gaap_RepaymentsOfLongTermDebt
Proceeds from stock options exercised	0	41	69
Stock tendered for payments of withholding taxes	(3,195)	(2,634)	(1,812)
Purchase of treasury stock	(18,024)	(13,791)	(11,208)
Capital lease payments	(2,449)	(2,329)	(2,454)
Excess tax benefits from share-based compensation	652	336	523
Net cash provided by (used in) financing activities	60,817	(10,131)	(14,882)
Effect of exchange rate changes on cash and cash equivalents	6	(2)	(5)
Net increase (decrease) in cash and cash equivalents	40,805	(1,796)	21,669
Cash and cash equivalents beginning of the year	68,964	70,760	49,091
Cash and cash equivalents end of the year	109,769	68,964	70,760
Supplemental disclosures of cash paid for:
Interest	1,532us-gaap_InterestPaid	1,201us-gaap_InterestPaid	1,200us-gaap_InterestPaid
Income taxes	$ 20,189us-gaap_IncomeTaxesPaid	$ 29,728us-gaap_IncomeTaxesPaid	$ 28,638us-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.