Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total Revenue	$ 335,208	$ 326,738
Flex revenue
Disaggregation of Revenue [Line Items]
Total Revenue	326,109	314,981
Direct Hire revenue
Disaggregation of Revenue [Line Items]
Total Revenue	9,099	11,757
Tech
Disaggregation of Revenue [Line Items]
Total Revenue	266,784	255,643
Tech | Flex revenue
Disaggregation of Revenue [Line Items]
Total Revenue	262,569	250,216
Tech | Direct Hire revenue
Disaggregation of Revenue [Line Items]
Total Revenue	4,215	5,427
FA
Disaggregation of Revenue [Line Items]
Total Revenue	68,424	71,095
FA | Flex revenue
Disaggregation of Revenue [Line Items]
Total Revenue	63,540	64,765
FA | Direct Hire revenue
Disaggregation of Revenue [Line Items]
Total Revenue	$ 4,884	$ 6,330