Franchising and Marketing Activities Change in the Number of Franchised and Brokerage Outlets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) franchisedandcompanyownedoffices	Dec. 31, 2023 USD ($) Brokerage_Offices	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) franchisedandcompanyownedoffices	Dec. 31, 2021 USD ($) franchisedandcompanyownedoffices
Franchisee Conversion Notes and Development Advance Notes
Change in Number of Franchised and Company Owned Outlets [Roll Forward]
Franchise conversion and development advance notes | $	$ 174	$ 174	$ 174	$ 182
Forgiveness of Franchise Conversion and Development Advance Notes, Charge to Operations | $			$ (34)	$ (45)	$ (32)
Franchise Group
Change in Number of Franchised and Company Owned Outlets [Roll Forward]
Beginning balance	19,824			20,355	19,386
Additions	571			548	1,583
Terminations/Closures	(2,092)			(1,079)	(614)
Ending balance	18,303			19,824	20,355
Owned Brokerage Group
Change in Number of Franchised and Company Owned Outlets [Roll Forward]
Beginning balance	679			675	673
Additions	5			46	25
Terminations/Closures	(61)			(42)	(23)
Ending balance	623	620		679	675