Variable Interest Entities - Consolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 313,003.3	$ 313,663.6
Total liabilities	301,408.3	302,194.6
Redeemable noncontrolling interest	326.7	337.7	$ 370.8	$ 248.9
Aggregate consolidated variable interest entities
Carrying amounts of consolidated VIE assets and liabilities
Total assets	37,596.6	35,834.9
Total liabilities	34,743.0	33,051.8
Redeemable noncontrolling interest	298.8	309.9
Mandatory retirement savings funds
Carrying amounts of consolidated VIE assets and liabilities
Total assets	35,005.8	33,130.4
Total liabilities	34,658.5	32,802.2
Real estate VIE
Carrying amounts of consolidated VIE assets and liabilities
Total assets	848.5	814.3
Total liabilities	41.8	69.4
Sponsored investment funds
Carrying amounts of consolidated VIE assets and liabilities
Total assets	697.1	833.7
Total liabilities	23.1	160.3
Redeemable noncontrolling interest	298.8	309.9
Residential mortgage loans VIE
Carrying amounts of consolidated VIE assets and liabilities
Total assets	790.6	806.5
Total liabilities	19.6	19.9
Asset-backed limited partnership
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 254.6	$ 250.0