Business and Organization (Details)	9 Months Ended
	Sep. 30, 2021 country Office item
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Percentage of Company consisting of franchises	100.00%
Minimum
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of agents | item	140,000
Number of offices | Office	8,000
Number of countries in which entity operates | country	110
Mortgage
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Percentage of Company consisting of franchises	100.00%