Condensed Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Operations [Abstract]
Net service revenues	$ 984,668	$ 817,258	$ 2,803,503	$ 2,323,521
Direct costs of services, consisting of payroll, payroll taxes, insurance costs and reimbursable expenses	592,765	508,118	1,701,223	1,456,395
Gross margin	391,903	309,140	1,102,280	867,126
Selling, general and administrative expenses	319,817	271,978	924,705	795,165
Amortization of intangible assets	39	46	118	362
Interest income, net	(148)	(153)	(598)	(321)
Income before income taxes	72,195	37,269	178,055	71,920
Provision for income taxes	28,027	16,645	70,757	30,641
Net income	44,168	20,624	107,298	41,279
Net income available to common stockholders-diluted	$ 43,556	$ 20,099	$ 105,740	$ 39,430
Net income per share (Note J):
Basic	$ 0.31	$ 0.14	$ 0.75	$ 0.28
Diluted	$ 0.31	$ 0.14	$ 0.74	$ 0.27
Shares:
Basic	139,449	142,230	141,118	143,182
Diluted	140,433	143,000	142,373	144,327
Cash dividends declared per share	$ 0.14	$ 0.13	$ 0.42	$ 0.39