Segment Reporting - Revenues and Adjusted Segment Earnings before Interest, Taxes, Depreciation and Amortization for Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Revenues	$ 3,788,857	$ 3,698,652	$ 3,489,242
Total segment gross profit	1,217,475	1,181,926	1,135,026
Operating Segments
Segment Reporting Information [Line Items]
Revenues	3,788,857	3,698,652	3,489,242
Compensation expenses	2,252,901	2,185,736	2,049,846
Other segment items	318,481	330,990	304,370
Direct costs	2,571,382	2,516,726	2,354,216
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	17,200	15,300	2,900
Corporate Finance
Segment Reporting Information [Line Items]
Total segment gross profit	537,103	453,750	431,971
Corporate Finance | Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,550,969	1,391,206	1,346,678
Compensation expenses	919,921	850,959	826,228
Other segment items	93,945	86,497	88,479
Direct costs	1,013,866	937,456	914,707
FLC
Segment Reporting Information [Line Items]
Total segment gross profit	274,073	225,185	216,787
FLC | Operating Segments
Segment Reporting Information [Line Items]
Revenues	764,687	690,211	654,105
Compensation expenses	465,896	432,157	400,457
Other segment items	24,718	32,869	36,861
Direct costs	490,614	465,026	437,318
Economic Consulting
Segment Reporting Information [Line Items]
Total segment gross profit	142,356	235,133	218,677
Economic Consulting | Operating Segments
Segment Reporting Information [Line Items]
Revenues	720,829	863,557	771,374
Compensation expenses	527,598	568,286	509,100
Other segment items	50,875	60,138	43,597
Direct costs	578,473	628,424	552,697
Technology
Segment Reporting Information [Line Items]
Total segment gross profit	123,937	145,118	148,512
Technology | Operating Segments
Segment Reporting Information [Line Items]
Revenues	373,883	417,637	387,855
Compensation expenses	148,234	152,107	134,576
Other segment items	101,712	120,412	104,767
Direct costs	249,946	272,519	239,343
Strategic Communications
Segment Reporting Information [Line Items]
Total segment gross profit	140,006	122,740	119,079
Strategic Communications | Operating Segments
Segment Reporting Information [Line Items]
Revenues	378,489	336,041	329,230
Compensation expenses	191,252	182,227	179,485
Other segment items	47,231	31,074	30,666
Direct costs	$ 238,483	$ 213,301	$ 210,151