Reportable Segments - Operations of Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total net service revenues	$ 333,992	$ 322,201
Gross profit	97,135	97,189
Operating expenses	87,913	88,450
Income before income taxes	9,222	8,739
Flex revenues
Segment Reporting Information [Line Items]
Total net service revenues	322,487	309,636
Direct Hire revenues
Segment Reporting Information [Line Items]
Total net service revenues	11,505	12,565
Tech
Segment Reporting Information [Line Items]
Total net service revenues	222,045	216,588
Gross profit	61,100	61,791
Tech | Flex revenues
Segment Reporting Information [Line Items]
Total net service revenues	216,886	211,209
Tech | Direct Hire revenues
Segment Reporting Information [Line Items]
Total net service revenues	5,159	5,379
FA
Segment Reporting Information [Line Items]
Total net service revenues	87,295	82,492
Gross profit	28,655	28,821
FA | Flex revenues
Segment Reporting Information [Line Items]
Total net service revenues	80,949	75,306
FA | Direct Hire revenues
Segment Reporting Information [Line Items]
Total net service revenues	6,346	7,186
GS
Segment Reporting Information [Line Items]
Total net service revenues	24,652	23,121
Gross profit	7,380	6,577
GS | Flex revenues
Segment Reporting Information [Line Items]
Total net service revenues	24,652	23,121
GS | Direct Hire revenues
Segment Reporting Information [Line Items]
Total net service revenues	$ 0	$ 0