Revenue from Contract with Customer - Real Estate Services (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 25,150	$ 20,952	$ 19,844
Real estate
Disaggregation of Revenue [Line Items]
Total operating revenue	6,215	5,396	4,473
HomeServices | Real estate
Disaggregation of Revenue [Line Items]
Customer revenue	5,583	4,596	4,096
Other revenue	632	800	377
Total operating revenue	6,215	5,396	4,473
HomeServices | Brokerage
Disaggregation of Revenue [Line Items]
Customer revenue	5,498	4,520	4,028
HomeServices | Franchise
Disaggregation of Revenue [Line Items]
Customer revenue	$ 85	$ 76	$ 68