Expenses - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 203	$ 78
BBH Investor Services
Restructuring Cost and Reserve [Line Items]
Acquisitions costs		(65)
Restructuring charges		8
Compensation and Employee Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	182	50
Occupancy Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 21	$ 20