Franchising and Marketing Activities Change in the Number of Franchised and Brokerage Outlets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) franchisedandcompanyownedoffices	Dec. 31, 2021 USD ($) Brokerage_Offices	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) franchisedandcompanyownedoffices	Dec. 31, 2019 USD ($) franchisedandcompanyownedoffices
Franchised (domestic and international):
Change in Number of Franchised and Company Owned Outlets [Roll Forward]
Beginning balance	19,386			17,776	15,830
Additions	1,583			2,109	2,399
Terminations/Closures	(614)			(499)	(453)
Ending balance	20,355			19,386	17,776
Company owned:
Change in Number of Franchised and Company Owned Outlets [Roll Forward]
Beginning balance	673			713	755
Additions	25			5	4
Terminations/Closures	(23)			(45)	(46)
Ending balance	675	680		673	713
Franchisee Conversion Notes and Development Advance Notes
Change in Number of Franchised and Company Owned Outlets [Roll Forward]
Franchise conversion and development advance notes | $	$ 164	$ 164	$ 164	$ 155
Forgiveness of franchise conversion and development advance notes | $			$ 32	$ 32	$ 29