Business Segments - Reconciliation of Revenue and Operating Income by Reportable Segment to Consolidated Results (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Service revenues	$ 5,795,837	$ 6,392,517	$ 7,238,142
Segment costs of services	3,529,844	3,801,252	4,157,942
Compensation expenses	1,336,622	1,428,108	1,561,661
Other	592,601	607,664	627,925
Segment selling, general and administrative expenses	1,929,223	2,035,772	2,189,586
Segment income	336,770	555,493	890,614
Amortization of intangible assets	1,217	2,883	1,667
Interest income, net	(22,118)	(23,973)	(8,008)
Income before income taxes	357,671	576,583	896,955
Service revenues	(5,795,837)	(6,392,517)	(7,238,142)
Contract Talent Solutions
Segment Reporting Information [Line Items]
Service revenues	3,357,872	3,895,332	4,532,847
Segment costs of services	2,041,348	2,346,020	2,728,818
Compensation expenses	884,121	934,024	973,341
Other	301,885	322,473	338,407
Segment selling, general and administrative expenses	1,186,006	1,256,497	1,311,748
Segment income	130,518	292,815	492,281
Service revenues	(3,357,872)	(3,895,332)	(4,532,847)
Contract Talent Solutions | Elimination Of Intersegment Revenues
Segment Reporting Information [Line Items]
Service revenues	(471,777)	(442,326)	(552,231)
Service revenues	471,777	442,326	552,231
Permanent Placement Talent Solutions
Segment Reporting Information [Line Items]
Service revenues	487,204	567,486	725,155
Segment costs of services	985	1,105	1,449
Compensation expenses	359,205	405,747	506,006
Other	80,962	85,630	90,078
Segment selling, general and administrative expenses	440,167	491,377	596,084
Segment income	46,052	75,004	127,622
Service revenues	(487,204)	(567,486)	(725,155)
Protiviti
Segment Reporting Information [Line Items]
Service revenues	1,950,761	1,929,699	1,980,140
Segment costs of services	1,487,511	1,454,127	1,427,675
Compensation expenses	93,296	88,337	82,314
Other	209,754	199,561	199,440
Segment selling, general and administrative expenses	303,050	287,898	281,754
Segment income	160,200	187,674	270,711
Service revenues	(1,950,761)	(1,929,699)	(1,980,140)
Contract Talent Solutions And Protiviti | Elimination Of Intersegment Revenues
Segment Reporting Information [Line Items]
Service revenues	(471,800)	(442,300)	(552,200)
Service revenues	$ 471,800	$ 442,300	$ 552,200