Revenue Recognition - Schedule of Revenue Disaggregated by Line of Business (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total service revenues	$ 1,300,179	$ 1,351,907
Total contract talent solutions
Disaggregation of Revenue [Line Items]
Total service revenues	725,016	763,205
Permanent placement talent solutions
Disaggregation of Revenue [Line Items]
Total service revenues	109,004	112,091
Protiviti
Disaggregation of Revenue [Line Items]
Total service revenues	466,159	476,611
Elimination of intersegment revenues | Total contract talent solutions
Disaggregation of Revenue [Line Items]
Total service revenues	(116,830)	(117,897)
Finance and accounting | Total contract talent solutions
Disaggregation of Revenue [Line Items]
Total service revenues	538,753	562,933
Administrative and customer support | Total contract talent solutions
Disaggregation of Revenue [Line Items]
Total service revenues	149,335	165,627
Technology | Total contract talent solutions
Disaggregation of Revenue [Line Items]
Total service revenues	$ 153,758	$ 152,542