Reportable Segments - Operations of Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net service revenues	$ 337,353	$ 302,758	$ 649,964	$ 584,782
Gross profit	106,038	94,386	200,778	177,912
Operating expenses	86,612	81,254	171,814	157,684
Income from continuing operations, before income taxes	19,426	13,132	28,964	20,228
Flexible Billings
Segment Reporting Information [Line Items]
Net service revenues	322,910	290,168	623,442	562,502
Direct Hire Fees
Segment Reporting Information [Line Items]
Net service revenues	14,443	12,590	26,522	22,280
Technology
Segment Reporting Information [Line Items]
Net service revenues	232,164	211,201	445,803	407,672
Gross profit	68,637	61,564	128,854	116,619
Technology | Flexible Billings
Segment Reporting Information [Line Items]
Net service revenues	225,873	206,165	434,311	398,628
Technology | Direct Hire Fees
Segment Reporting Information [Line Items]
Net service revenues	6,291	5,036	11,492	9,044
Finance and Accounting
Segment Reporting Information [Line Items]
Net service revenues	80,925	67,611	153,997	130,393
Gross profit	29,830	25,492	55,519	47,368
Finance and Accounting | Flexible Billings
Segment Reporting Information [Line Items]
Net service revenues	72,773	60,057	138,967	117,157
Finance and Accounting | Direct Hire Fees
Segment Reporting Information [Line Items]
Net service revenues	8,152	7,554	15,030	13,236
Government Solutions
Segment Reporting Information [Line Items]
Net service revenues	24,264	23,946	50,164	46,717
Gross profit	7,571	7,330	16,405	13,925
Government Solutions | Flexible Billings
Segment Reporting Information [Line Items]
Net service revenues	24,264	23,946	50,164	46,717
Government Solutions | Direct Hire Fees
Segment Reporting Information [Line Items]
Net service revenues	$ 0	$ 0	$ 0	$ 0