REVENUE RECOGNITION - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Total revenues	$ 283,449	$ 271,366	$ 497,782	$ 524,769
New York City
Disaggregation of Revenue [Line Items]
Total revenues	71,129	88,270	131,852	172,015
Northeast
Disaggregation of Revenue [Line Items]
Total revenues	53,223	50,099	92,474	93,464
Southeast
Disaggregation of Revenue [Line Items]
Total revenues	112,589	78,046	190,174	159,819
West
Disaggregation of Revenue [Line Items]
Total revenues	46,433	54,951	83,133	99,471
International
Disaggregation of Revenue [Line Items]
Total revenues	75	0	149	0
Commission and other brokerage income - existing home sales
Disaggregation of Revenue [Line Items]
Total revenues	261,763	243,755	459,629	463,762
Commission and other brokerage income - existing home sales \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	64,516	71,039	116,008	137,256
Commission and other brokerage income - existing home sales \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	53,194	49,789	92,445	92,784
Commission and other brokerage income - existing home sales \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	101,095	72,872	174,358	142,271
Commission and other brokerage income - existing home sales \| West
Disaggregation of Revenue [Line Items]
Total revenues	42,883	50,055	76,669	91,451
Commission and other brokerage income - existing home sales \| International
Disaggregation of Revenue [Line Items]
Total revenues	75	0	149	0
Commission and other brokerage income - development marketing
Disaggregation of Revenue [Line Items]
Total revenues	18,440	14,261	32,455	35,397
Commission and other brokerage income - development marketing \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	6,512	6,835	15,733	15,005
Commission and other brokerage income - development marketing \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	0	111	0	263
Commission and other brokerage income - development marketing \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	11,491	5,174	15,812	17,548
Commission and other brokerage income - development marketing \| West
Disaggregation of Revenue [Line Items]
Total revenues	437	2,141	910	2,581
Commission and other brokerage income - development marketing \| International
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Property management revenue
Disaggregation of Revenue [Line Items]
Total revenues		10,465		19,957
Property management revenue \| New York City
Disaggregation of Revenue [Line Items]
Total revenues		10,273		19,555
Property management revenue \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues		192		402
Property management revenue \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues		0		0
Property management revenue \| West
Disaggregation of Revenue [Line Items]
Total revenues		0		0
Property management revenue \| International
Disaggregation of Revenue [Line Items]
Total revenues		0		0
Other ancillary services
Disaggregation of Revenue [Line Items]
Total revenues	3,246	2,885	5,698	5,653
Other ancillary services \| New York City
Disaggregation of Revenue [Line Items]
Total revenues	101	123	111	199
Other ancillary services \| Northeast
Disaggregation of Revenue [Line Items]
Total revenues	29	7	29	15
Other ancillary services \| Southeast
Disaggregation of Revenue [Line Items]
Total revenues	3	0	4	0
Other ancillary services \| West
Disaggregation of Revenue [Line Items]
Total revenues	3,113	2,755	5,554	5,439
Other ancillary services \| International
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0