REVENUE RECOGNITION - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 995,627	$ 955,578	$ 1,153,177
New York City
Disaggregation of Revenue [Line Items]
Total revenues	326,617	335,620	451,797
Northeast
Disaggregation of Revenue [Line Items]
Total revenues	191,058	179,649	210,422
Southeast
Disaggregation of Revenue [Line Items]
Total revenues	284,507	250,738	277,335
West
Disaggregation of Revenue [Line Items]
Total revenues	193,445	189,571	213,623
Commission and other brokerage income - existing home sales
Disaggregation of Revenue [Line Items]
Total revenues	878,775	849,874	1,028,480
Commission and other brokerage income - existing home sales \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	262,937	271,586	359,417
Commission and other brokerage income - existing home sales \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	189,625	177,222	207,932
Commission and other brokerage income - existing home sales \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	248,617	226,231	263,468
Commission and other brokerage income - existing home sales \| West
Disaggregation of Revenue [Line Items]
Total revenues	177,596	174,835	197,663
Commission and other brokerage income - development marketing
Disaggregation of Revenue [Line Items]
Total revenues	67,782	56,195	71,405
Commission and other brokerage income - development marketing \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	27,171	27,376	53,773
Commission and other brokerage income - development marketing \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	396	938	654
Commission and other brokerage income - development marketing \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	35,871	24,507	13,867
Commission and other brokerage income - development marketing \| West
Disaggregation of Revenue [Line Items]
Total revenues	4,344	3,374	3,111
Property management revenue
Disaggregation of Revenue [Line Items]
Total revenues	36,785	35,542	36,022
Property management revenue \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	36,027	34,798	35,421
Property management revenue \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	758	744	601
Property management revenue \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Property management revenue \| West
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Escrow and title fees
Disaggregation of Revenue [Line Items]
Total revenues	12,285	13,967	17,270
Escrow and title fees \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	482	1,860	3,186
Escrow and title fees \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	279	745	1,235
Escrow and title fees \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	19	0	0
Escrow and title fees \| West
Disaggregation of Revenue [Line Items]
Total revenues	$ 11,505	$ 11,362	$ 12,849