Segment Information - Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Total revenue	$ 329,701	$ 266,001	$ 282,293
Real Estate
Segment Reporting Information
Total revenue	235,124	190,792	199,636
Mortgage
Segment Reporting Information
Total revenue	10,051	6,610	4,542
Marketing Funds fees
Segment Reporting Information
Total revenue	82,391	64,402	72,299
Other.
Segment Reporting Information
Total revenue	2,135	4,197	5,816
Continuing franchise fees
Segment Reporting Information
Total revenue	118,504	90,217	99,928
Continuing franchise fees | Real Estate
Segment Reporting Information
Total revenue	110,613	84,863	95,854
Continuing franchise fees | Mortgage
Segment Reporting Information
Total revenue	7,891	5,354	4,074
Annual Dues
Segment Reporting Information
Total revenue	35,549	35,075	35,409
Annual Dues | Real Estate
Segment Reporting Information
Total revenue	35,549	35,075	35,409
Broker fees
Segment Reporting Information
Total revenue	65,456	50,028	45,990
Broker fees | Real Estate
Segment Reporting Information
Total revenue	65,456	50,028	45,990
Franchise sales and other revenue
Segment Reporting Information
Total revenue	27,801	26,279	28,667
Franchise sales and other revenue | Real Estate
Segment Reporting Information
Total revenue	23,506	20,826	22,383
Franchise sales and other revenue | Mortgage
Segment Reporting Information
Total revenue	$ 2,160	$ 1,256	$ 468