Investments and Fair Value Measurements (Quantitative Information about Level 3 Fair Value Measurements) (Details) - Recurring $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liability	$ 2,646
Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liability	2,646
Significant Unobservable Inputs (Level 3) | Monte Carlo simulation model | Estimated fair value of the Douglas Elliman reporting unit
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Estimated fair value of the Douglas Elliman reporting unit	$ 776,351
Significant Unobservable Inputs (Level 3) | Monte Carlo simulation model | Risk-free rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of contingent liability, measurement input term	9 months
Measurement input	0.0039
Significant Unobservable Inputs (Level 3) | Monte Carlo simulation model | Leverage-adjusted equity volatility of peer firms
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.2613