Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2016	Aug. 08, 2016
Entity Registrant Name	RMR Group Inc.
Entity Central Index Key	0001644378
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q3
Class A common shares
Entity Common Stock, Shares Outstanding		15,007,500
Class B-1 common shares
Entity Common Stock, Shares Outstanding		1,000,000
Class B-2 common shares
Entity Common Stock, Shares Outstanding		15,000,000