Reportable Segments - Operations of Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Total net service revenues	$ 336,460	$ 341,575	$ 993,708	$ 991,539
Gross profit	105,380	109,821	308,851	310,599
Operating expenses	90,656	87,209	267,663	259,023
Income before income taxes	14,724	22,612	41,188	51,576
Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	323,484	327,439	954,593	950,881
Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	12,976	14,136	39,115	40,658
Tech
Segment Reporting Information [Line Items]
Total net service revenues	225,524	232,113	666,670	677,916
Gross profit	65,173	69,128	193,132	197,982
Tech | Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	220,376	226,381	650,997	660,692
Tech | Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	5,148	5,732	15,673	17,224
FA
Segment Reporting Information [Line Items]
Total net service revenues	84,118	85,111	251,807	239,108
Gross profit	30,439	31,710	90,695	87,229
FA | Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	76,290	76,707	228,365	215,674
FA | Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	7,828	8,404	23,442	23,434
GS
Segment Reporting Information [Line Items]
Total net service revenues	26,818	24,351	75,231	74,515
Gross profit	9,768	8,983	25,024	25,388
GS | Flexible Billings
Segment Reporting Information [Line Items]
Total net service revenues	26,818	24,351	75,231	74,515
GS | Direct Hire Fees
Segment Reporting Information [Line Items]
Total net service revenues	$ 0	$ 0	$ 0	$ 0