Variable Interest Entities - Consolidated VIEs (Details) - USD ($) $ in Millions	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 308,777.3		$ 305,046.7
Total liabilities	297,440.9		293,836.1
Redeemable noncontrolling interest	277.4	$ 370.8	248.9	$ 266.7	$ 272.7	$ 262.0
Aggregate consolidated variable interest entities
Carrying amounts of consolidated VIE assets and liabilities
Total assets	35,822.9		37,511.3
Total liabilities	32,937.8		34,778.5
Redeemable noncontrolling interest	252.7		226.4
Mandatory retirement savings funds
Carrying amounts of consolidated VIE assets and liabilities
Total assets	33,178.0		35,034.4
Total liabilities	32,849.7		34,688.3
Real estate VIE
Carrying amounts of consolidated VIE assets and liabilities
Total assets	920.3		829.1
Total liabilities	56.0		63.0
Sponsored investment funds
Carrying amounts of consolidated VIE assets and liabilities
Total assets	637.7		523.8
Total liabilities	11.8		6.3
Redeemable noncontrolling interest	252.7		226.4
Residential mortgage loans VIE
Carrying amounts of consolidated VIE assets and liabilities
Total assets	836.4		874.7
Total liabilities	20.3		20.9
Asset-backed limited partnership
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 250.5		$ 249.3