Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Net service revenues	$ 1,205,563us-gaap_SalesRevenueServicesNet	$ 1,084,342us-gaap_SalesRevenueServicesNet
Direct costs of services, consisting of payroll, payroll taxes, benefit costs and reimbursable expenses	711,476us-gaap_CostOfServices	645,847us-gaap_CostOfServices
Gross margin	494,087us-gaap_GrossProfit	438,495us-gaap_GrossProfit
Selling, general and administrative expenses	365,985	336,386
Amortization of intangible assets	0us-gaap_AmortizationOfIntangibleAssets	333us-gaap_AmortizationOfIntangibleAssets
Interest income, net	(72)us-gaap_InterestIncomeExpenseNet	(238)us-gaap_InterestIncomeExpenseNet
Income before income taxes	128,174	102,014
Provision for income taxes	50,252us-gaap_IncomeTaxExpenseBenefit	40,463us-gaap_IncomeTaxExpenseBenefit
Net income	$ 77,922us-gaap_NetIncomeLoss	$ 61,551us-gaap_NetIncomeLoss
Net income per share:
Basic (in usd per share)	$ 0.59us-gaap_EarningsPerShareBasic	$ 0.45us-gaap_EarningsPerShareBasic
Diluted (in usd per share)	$ 0.58us-gaap_EarningsPerShareDiluted	$ 0.45us-gaap_EarningsPerShareDiluted
Shares:
Basic (in shares)	133,077	135,333
Diluted (in shares)	134,286	136,161
Cash dividends declared per share	$ 0.20	$ 0.18

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.

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