Fair Value Measures and Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Sep. 30, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investment, Other-than-Temporary Impairment	$ 12.4
Fair Value, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	43.5	$ 8.8
Investments, Fair Value Disclosure	113.1	68.1
Fair Value, Recurring | Fair Value, Inputs, Level 1 | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	42.3	35.0
Fair Value, Recurring | Fair Value, Inputs, Level 1 | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	2.4	1.5
Fair Value, Recurring | Fair Value, Inputs, Level 1 | Wealth Advisors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	24.9	22.8
Fair Value, Recurring | Fair Value, Inputs, Level 1 | SmartX
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0.0	0.0
Investments, Fair Value Disclosure	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 2 | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 2 | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 2 | Wealth Advisors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 2 | SmartX
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0.0	0.0
Investments, Fair Value Disclosure	24.7	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 3 | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 3 | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 3 | Wealth Advisors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 3 | SmartX
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	24.7
Estimate of Fair Value Measurement | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	43.5	8.8
Investments, Fair Value Disclosure	137.8	68.1
Estimate of Fair Value Measurement | Fair Value, Recurring | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	42.3	35.0
Estimate of Fair Value Measurement | Fair Value, Recurring | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	2.4	1.5
Estimate of Fair Value Measurement | Fair Value, Recurring | Wealth Advisors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	24.9	$ 22.8
Estimate of Fair Value Measurement | Fair Value, Recurring | SmartX
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Cost	$ 24.7