Noncontrolling Interests - Schedule of Noncontrolling Interest (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	$ 732.2	$ 698.2
Ark
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	471.5	465.2
Kudu
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	144.1	141.2
HG Global
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	(20.0)	(18.4)
Distinguished
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	76.0	73.7
WTM Partners
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	55.8	31.0
Other Operations
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	4.8	5.5
Ark - Management Equity Incentive
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	59.2	58.6
Kudu - Management Equity Incentive
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	47.6	52.3
Distinguished - Management Equity Incentives
Noncontrolling Interest [Line Items]
Nonredeemable Noncontrolling Equity	$ 38.5	$ 33.3
Ark
Noncontrolling Interest [Line Items]
Nonredeemable noncontrolling percentage	27.90%	27.90%
Kudu
Noncontrolling Interest [Line Items]
Nonredeemable noncontrolling percentage	8.70%	8.80%
HG Global
Noncontrolling Interest [Line Items]
Nonredeemable noncontrolling percentage	3.10%	3.10%
Distinguished
Noncontrolling Interest [Line Items]
Nonredeemable noncontrolling percentage	13.50%	13.10%
WTM Partners
Noncontrolling Interest [Line Items]
Nonredeemable noncontrolling percentage		34.50%