Revenue Recognition - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Contract with customer, liability	$ 942			$ 740
Cumulative effect of new accounting standard, net of tax				(179)
Contingency period (or less)	90 days
Required payment period (typically less)	90 days
Direct Hire revenue
Disaggregation of Revenue [Line Items]
Contract with customer, refund liability	$ 500			500
Fixed-price Contract | GS | Flex revenue
Disaggregation of Revenue [Line Items]
Revenue, as a percent	40.60%	28.90%
Retained Earnings
Disaggregation of Revenue [Line Items]
Cumulative effect of new accounting standard, net of tax				$ (179)
Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Contract with customer, liability			$ 200
Accounting Standards Update 2014-09 | Retained Earnings
Disaggregation of Revenue [Line Items]
Cumulative effect of new accounting standard, net of tax			$ (200)