Net Income Attributable to RMR Inc (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Net Income Attributable to RMR Inc.
Income before income tax expense and equity in losses of investees	$ 207,889	$ 75,873
Add: RMR Inc. franchise tax expense and interest income	159	154
Less: tax receivable agreement remeasurement	(24,710)	0
Less: equity in losses of investees	(222)	0
Less: fees from services provided prior to the UP-C Transaction	(128)	0
Net income before noncontrolling interest	182,988	76,027
Less: noncontrolling interest	(88,076)	(36,690)
Net income attributable to RMR Inc. before income tax expense	94,912	39,337
Less: income tax expense attributable to RMR Inc.	(48,343)	(15,673)
Add: tax receivable agreement remeasurement	24,710	0
Less: RMR Inc. franchise tax expense and interest income	(159)	(154)
Net income attributable to RMR Inc.	$ 71,120	$ 23,510