Business and Organization (Details) shares in Millions		12 Months Ended
	Dec. 31, 2017 segment country Vote Office class item	Dec. 31, 2017 country Vote Office class item	Dec. 31, 2015 shares	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock issued at initial public offering | shares			5.2
Number of offices | Office	7,000	7,000
Number of countries in which entity operates | country	100	100
Percentage of Company consisting of franchises		100.00%
Number Of Reportable Segments | segment	1
Ownership percentage	30.00%	30.00%
Number of votes for common class holders, as a multiple of the aggregate number of Common Units in RMCO held by the holder upon occurrence of certain events (as a percent)	1	1
Number of classes of common stock | class	2	2
RMCO, LLC
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Parent economic interest in RMCO (as a percent)	58.49%	58.49%		58.43%
Non-controlling unitholders ownership of common units in RMCO as a percentage	41.51%	41.51%		41.57%
RIHI | RMCO, LLC
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Non-controlling unitholders ownership of common units in RMCO as a percentage	41.51%	41.51%
Common Class A
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of votes per share held	1	1
Common Units | RMCO, LLC
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of votes for common class holders, as a multiple of the aggregate number of Common Units in RMCO held by the holder (as a percent)		1
Common Class B | RMCO, LLC
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Ratio of votes in parent company to number of L L C common units held	2	2
Number of votes for common class holders, for each Common Unit in RMCO held by the holder (in votes)		2
Minimum
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of agents | item	115,000	115,000