Segment Reporting - Revenues and Adjusted Segment Earnings before Interest, Taxes, Depreciation and Amortization for Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Revenues	$ 806,706	$ 723,620
Adjusted Segment EBITDA	112,746	121,067
Corporate Finance
Segment Reporting Information [Line Items]
Revenues	299,987	253,329
Adjusted Segment EBITDA	55,020	53,539
FLC
Segment Reporting Information [Line Items]
Revenues	173,404	153,896
Adjusted Segment EBITDA	18,611	17,257
Economic Consulting
Segment Reporting Information [Line Items]
Revenues	169,595	165,977
Adjusted Segment EBITDA	14,193	21,195
Technology
Segment Reporting Information [Line Items]
Revenues	90,618	80,484
Adjusted Segment EBITDA	15,366	13,363
Strategic Communications
Segment Reporting Information [Line Items]
Revenues	73,102	69,934
Adjusted Segment EBITDA	$ 9,556	$ 15,713