COST-SAVING INITIATIVES - Expenses Associated with Cost Savings Initiatives (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cost Saving initiatives [Line Items]
Restructuring charges	$ 48,729	$ 20,740
Severance and other employee termination expenses (included in "compensation and benefits" expense)
Cost Saving initiatives [Line Items]
Restructuring charges	46,610	20,740
Other
Cost Saving initiatives [Line Items]
Restructuring charges	2,119
Operating Segments | Financial Advisory
Cost Saving initiatives [Line Items]
Restructuring charges	33,481	8,777
Operating Segments | Financial Advisory | Severance and other employee termination expenses (included in "compensation and benefits" expense)
Cost Saving initiatives [Line Items]
Restructuring charges	32,773	8,777
Operating Segments | Financial Advisory | Other
Cost Saving initiatives [Line Items]
Restructuring charges	708
Operating Segments | Asset Management
Cost Saving initiatives [Line Items]
Restructuring charges	11,559	11,235
Operating Segments | Asset Management | Severance and other employee termination expenses (included in "compensation and benefits" expense)
Cost Saving initiatives [Line Items]
Restructuring charges	11,545	11,235
Operating Segments | Asset Management | Other
Cost Saving initiatives [Line Items]
Restructuring charges	14
Corporate
Cost Saving initiatives [Line Items]
Restructuring charges	3,689	728
Corporate | Severance and other employee termination expenses (included in "compensation and benefits" expense)
Cost Saving initiatives [Line Items]
Restructuring charges	2,292	$ 728
Corporate | Other
Cost Saving initiatives [Line Items]
Restructuring charges	$ 1,397