Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Revenues, net	$ 589,505	$ 713,368	$ 404,979
Expenses:
Compensation and benefits	121,386	114,529	108,763
Equity based compensation	7,828	9,040	10,423
Separation costs	1,881	7,050	3,730
Total compensation and benefits expense	131,095	130,619	122,916
General and administrative	26,514	28,706	27,149
Other client company reimbursable expenses	360,572	354,540	0
Transaction and acquisition related costs	1,618	698	1,697
Depreciation and amortization	968	1,017	1,248
Total expenses	520,767	515,580	153,010
Operating income	68,738	197,788	251,969
Interest and other income	4,451	8,770	4,546
Tax receivable agreement remeasurement	0	0	24,710
Impairment loss on Tremont Mortgage Trust investment	0	(6,213)	(4,359)
Equity in earnings (losses) of investees	1,545	719	(578)
Unrealized gain (loss) on equity method investment accounted for under the fair value option	3,151	(4,700)	0
Income (loss) before income tax expense	77,885	196,364	276,288
Income tax expense	(11,552)	(27,320)	(58,862)
Net income	66,333	169,044	217,426
Net income attributable to noncontrolling interest	(37,541)	(94,464)	(121,385)
Net income attributable to The RMR Group Inc.	$ 28,792	$ 74,580	$ 96,041
Weighted average number of shares outstanding, basic (in shares)	16,194	16,132	16,077
Weighted average common shares outstanding - diluted (in shares)	31,194	16,143	16,120
Net income attributable to RMR Inc. per common share - basic (in dollars per share)	$ 1.77	$ 4.59	$ 5.94
Net income attributable to The RMR Group Inc. per common share - diluted (in dollars per share)	$ 1.75	$ 4.59	$ 5.92
Total management and advisory services revenues
Revenues:
Revenues	$ 171,677	$ 301,338	$ 351,827
Management services
Revenues:
Revenues	168,766	178,075	191,594
Incentive business management fees
Revenues:
Revenues	0	120,094	155,881
Advisory services
Revenues:
Revenues	2,911	3,169	4,352
Total reimbursable costs
Revenues:
Revenues	417,828	412,030	53,152
Reimbursable compensation and benefits
Revenues:
Revenues	57,256	57,490	53,152
Other client company reimbursable expenses
Revenues:
Revenues	$ 360,572	$ 354,540	$ 0