Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Goodwill [Roll Forward]
Goodwill beginning of period	$ 1,234,569,000
Foreign currency translation adjustment	(3,924,000)
Goodwill end of period	1,230,645,000
Corporate Finance & Restructuring
Goodwill [Roll Forward]
Goodwill beginning of period	540,991,000
Foreign currency translation adjustment	(2,738,000)
Goodwill end of period	538,253,000
Accumulated impairment loss	0	$ 0
Forensic and Litigation Consulting
Goodwill [Roll Forward]
Goodwill beginning of period	213,415,000
Foreign currency translation adjustment	(426,000)
Goodwill end of period	212,989,000
Accumulated impairment loss	0	0
Economic Consulting
Goodwill [Roll Forward]
Goodwill beginning of period	268,482,000
Foreign currency translation adjustment	(158,000)
Goodwill end of period	268,324,000
Accumulated impairment loss	0	0
Technology
Goodwill [Roll Forward]
Goodwill beginning of period	96,802,000
Foreign currency translation adjustment	(13,000)
Goodwill end of period	96,789,000
Accumulated impairment loss	0	0
Strategic Communications
Goodwill [Roll Forward]
Goodwill beginning of period	114,879,000
Foreign currency translation adjustment	(589,000)
Goodwill end of period	114,290,000
Accumulated impairment loss	194,100,000	194,100,000
Goodwill	$ 308,400,000	$ 309,000,000