Reportable Segments - Operations of Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Total net service revenues	$ 335,047	$ 337,353	$ 657,248	$ 649,964
Gross profit	106,282	106,038	203,471	200,778
Operating expenses	88,557	86,612	177,007	171,814
Income before income taxes	17,725	19,426	26,464	28,964
Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	321,473	322,910	631,109	623,442
Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	13,574	14,443	26,139	26,522
Tech
Segment Reporting Information [Line Items]
Total net service revenues	224,558	232,164	441,146	445,803
Gross profit	66,168	68,637	127,959	128,854
Tech | Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	219,412	225,873	430,621	434,311
Tech | Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	5,146	6,291	10,525	11,492
FA
Segment Reporting Information [Line Items]
Total net service revenues	85,197	80,925	167,689	153,997
Gross profit	31,435	29,830	60,256	55,519
FA | Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	76,769	72,773	152,075	138,967
FA | Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	8,428	8,152	15,614	15,030
GS
Segment Reporting Information [Line Items]
Total net service revenues	25,292	24,264	48,413	50,164
Gross profit	8,679	7,571	15,256	16,405
GS | Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	25,292	24,264	48,413	50,164
GS | Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	$ 0	$ 0	$ 0	$ 0