Current Expected Credit Losses (CECL) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Current expected credit losses reserve	$ 2.4	$ 2.6	$ 1.9
Increase (decrease) in expected credit losses reserve	(0.2)	0.7
Loans, Forgivable Loans and Other Receivables from Employees and Partners, Net
Financing Receivable, Allowance for Credit Loss [Line Items]
Current expected credit losses reserve	1.7	1.6	1.1
Increase (decrease) in expected credit losses reserve	(0.1)	0.5
Accrued Commissions and Other Receivables, Net
Financing Receivable, Allowance for Credit Loss [Line Items]
Current expected credit losses reserve	0.7	1.0	$ 0.8
Increase (decrease) in expected credit losses reserve	$ (0.3)	$ 0.2