v3.26.1
REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregated Revenue (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]    
Revenue $ 897 $ 732
Commercial Real Estate Segment    
Disaggregation of Revenue [Line Items]    
Revenue 472 409
Residential Real Estate Segment    
Disaggregation of Revenue [Line Items]    
Revenue 425 323
CoStar | Commercial Real Estate Segment    
Disaggregation of Revenue [Line Items]    
Revenue 331 305
LoopNet | Commercial Real Estate Segment    
Disaggregation of Revenue [Line Items]    
Revenue 85 73
Other Commercial Real Estate | Commercial Real Estate Segment    
Disaggregation of Revenue [Line Items]    
Revenue $ 56 $ 31