Special Charges - Schedule of Special Charges By Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Special charges	$ 0	$ 7,103	$ 0
Operating Segments
Restructuring Cost and Reserve [Line Items]
Special charges		6,730
Operating Segments | Corporate Finance
Restructuring Cost and Reserve [Line Items]
Special charges		861
Operating Segments | FLC
Restructuring Cost and Reserve [Line Items]
Special charges		3,484
Operating Segments | Economic Consulting
Restructuring Cost and Reserve [Line Items]
Special charges		35
Operating Segments | Technology
Restructuring Cost and Reserve [Line Items]
Special charges		276
Operating Segments | Strategic Communications
Restructuring Cost and Reserve [Line Items]
Special charges		2,074
Unallocated corporate assets
Restructuring Cost and Reserve [Line Items]
Special charges		$ 373