Basis of Presentation (Details)	6 Months Ended
	Mar. 31, 2016 shares
ABP Trust
Ownership percentage	48.40%
Redeemable Class A membership units | ABP Trust
Membership units (in units)	15,000,000
RMR LLC
Ownership percentage	51.60%
RMR LLC | Class A membership units
Membership units (in units)	15,007,500
RMR LLC | Class B membership units
Membership units (in units)	1,000,000