Business Segment Information - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025 segment distributionChannel	Sep. 30, 2024
Segment Reporting [Abstract]
Number of operating segments | segment			1
Number of distribution channels | distributionChannel			3
Revenue Benchmark | Product Concentration Risk | Japan
Revenue, Major Customer [Line Items]
Concentration risk	13.00%	11.00%	12.00%	10.00%
Revenue Benchmark | Product Concentration Risk | Japan | Investment advisory and services fees
Revenue, Major Customer [Line Items]
Concentration risk	8.00%	7.00%	8.00%	7.00%