CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Revenues	$ 430,045us-gaap_SalesRevenueServicesNet	$ 406,851us-gaap_SalesRevenueServicesNet
Cost of services	294,170us-gaap_CostOfServices	278,696us-gaap_CostOfServices
Gross profit	135,875us-gaap_GrossProfit	128,155us-gaap_GrossProfit
Selling, general and administrative expenses	105,935	96,109
Amortization of intangible assets	4,869us-gaap_AmortizationOfIntangibleAssets	5,538us-gaap_AmortizationOfIntangibleAssets
Operating income	25,071us-gaap_OperatingIncomeLoss	26,508us-gaap_OperatingIncomeLoss
Interest expense, net	(3,067)us-gaap_InterestExpense	(3,328)us-gaap_InterestExpense
Income before income taxes	22,004	23,180
Provision for income taxes	8,981us-gaap_IncomeTaxExpenseBenefit	9,575us-gaap_IncomeTaxExpenseBenefit
Income from continuing operations	13,023	13,605
Gain on sale of discontinued operations, net of income taxes	25,703	0
Income from discontinued operations, net of income taxes	409	312
Net income	39,135us-gaap_NetIncomeLoss	13,917us-gaap_NetIncomeLoss
Basic earnings per common share:
Income from continuing operations	$ 0.25	$ 0.25
Discontinued operations	$ 0.51	$ 0.01
Net income	$ 0.76us-gaap_EarningsPerShareBasic	$ 0.26us-gaap_EarningsPerShareBasic
Diluted earnings per common share:
Income from continuing operations	$ 0.25	$ 0.25
Discontinued operations	$ 0.50	$ 0.00
Net income	$ 0.75us-gaap_EarningsPerShareDiluted	$ 0.25us-gaap_EarningsPerShareDiluted
Number of shares and share equivalents used to calculate earnings per share:
Basic	51,519	54,104
Diluted	52,209	54,975
Reconciliation of net income to comprehensive income:
Net income	39,135us-gaap_NetIncomeLoss	13,917us-gaap_NetIncomeLoss
Changes in fair value of derivatives, net of tax	47	44
Foreign currency translation adjustment, net of tax	(3,724)	(44)
Comprehensive income	$ 35,458us-gaap_ComprehensiveIncomeNetOfTax	$ 13,917us-gaap_ComprehensiveIncomeNetOfTax

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.