Reconciliation of Revenue and Operating Income by Reportable Segment to Consolidated Results (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net service revenues	$ 1,083,864	$ 1,075,119	$ 1,063,228	$ 1,023,684	$ 1,034,213	$ 1,033,173	$ 1,028,383	$ 1,015,444	$ 4,245,895	$ 4,111,213	$ 3,776,976
Operating income									398,277	343,446	249,418
Amortization of intangible assets									1,700	398	153
Interest income, net									(1,002)	(1,197)	(951)
Income before income taxes	103,894	103,713	100,596	89,376	97,242	94,467	72,272	80,264	397,579	344,245	250,216
Temporary and consultant staffing
Segment Reporting Information [Line Items]
Net service revenues									3,369,840	3,324,286	3,050,999
Operating income									301,185	276,826	209,101
Permanent placement staffing
Segment Reporting Information [Line Items]
Net service revenues									347,715	334,198	302,155
Operating income									54,390	55,745	35,340
Risk consulting and internal audit services
Segment Reporting Information [Line Items]
Net service revenues									528,340	452,729	423,822
Operating income									$ 42,702	$ 10,875	$ 4,977