Redeemable Non-Controlling Interests (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Redeemable Non-controlling Interests
Balance, beginning of period	$ 465.4	$ 673.9
Veritable Transaction	(16.8)	0.0
Decrease attributable to consolidated Affiliate sponsored investment products	(8.3)	(4.9)
Transfers to Other liabilities	(93.5)	(59.6)
Transfer (to) from Redeemable non-controlling interests	(8.9)	1.8	$ 3.9
Changes in redemption value	55.5	(145.8)
Balance, end of period	393.4	465.4	$ 673.9
Variable Interest Entity, Primary Beneficiary
Redeemable Non-controlling Interests
Balance, beginning of period	20.1
Balance, end of period	$ 11.8	$ 20.1
Minimum
Noncontrolling Interest [Line Items]
Term of conditional right put interest	5 years
Maximum
Noncontrolling Interest [Line Items]
Term of conditional right put interest	15 years