Reconciliation of Revenue and Operating Income (Loss) by Reportable Segment to Consolidated Results (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment Reporting Information [Line Items]
Net service revenues	$ 1,028,383	$ 937,966	$ 2,043,827	$ 1,818,835
Operating Income (Loss)	72,039	61,086	152,104	105,489
Amortization of intangible assets	52	40	87	79
Interest income, net	(285)	(238)	(519)	(450)
Income before income taxes	72,272	61,284	152,536	105,860
Temporary and consultant staffing
Segment Reporting Information [Line Items]
Net service revenues	829,008	752,369	1,658,665	1,467,051
Operating Income (Loss)	51,668	46,241	120,822	84,311
Permanent placement staffing
Segment Reporting Information [Line Items]
Net service revenues	89,141	80,663	172,003	148,267
Operating Income (Loss)	18,358	13,875	31,624	21,742
Risk consulting and internal audit services
Segment Reporting Information [Line Items]
Net service revenues	110,234	104,934	213,159	203,517
Operating Income (Loss)	$ 2,013	$ 970	$ (342)	$ (564)