CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock Series D	Cumulative Preferred Distributions	Common shares	Cumulative Common Distributions	Additional Paid-in-Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)
Balance at Dec. 31, 2013	$ 3,086,855	$ 208,107	$ (279,985)	$ 1,496	$ (3,558,369)	$ 4,109,600	$ 2,518,054	$ 15,952
Balance (in shares) at Dec. 31, 2013		11,600,000		149,606,024
Increase (Decrease) in Shareholders' Equity
Net income	197,185						197,185
Unrealized gain (loss) on investment in available for sale securities	9,852							9,852
Issuance of shares, net	6,446			$ 2		6,444
Issuance of shares, net (in shares)				222,200
Common share grants	2,508			$ 1		2,507
Share grants (in shares)				92,225
Distributions	(312,693)		(20,664)		(292,029)
Distribution to common shareholders of The RMR Group Inc. common stock	0
Balance at Dec. 31, 2014	2,990,153	$ 208,107	(300,649)	$ 1,499	(3,850,398)	4,118,551	2,715,239	25,804
Balance (in shares) at Dec. 31, 2014		11,600,000		149,920,449
Increase (Decrease) in Shareholders' Equity
Net income	166,418						166,418
Unrealized gain (loss) on investment in available for sale securities	(41,327)							(41,327)
Issuance of shares, net	45,262			$ 15		45,247
Issuance of shares, net (in shares)				1,553,119
Common share grants	2,532			$ 1		2,531
Share grants (in shares)				90,060
Common share repurchases	(418)					(418)
Common share repurchases (in shares)				(16,340)
Distributions	(320,627)		(20,664)		(299,963)
Distribution to common shareholders of The RMR Group Inc. common stock	(29,911)		0		(29,911)
Balance at Dec. 31, 2015	2,812,082	$ 208,107	(321,313)	$ 1,515	(4,180,272)	4,165,911	2,881,657	(15,523)
Balance (in shares) at Dec. 31, 2015		11,600,000		151,547,288
Increase (Decrease) in Shareholders' Equity
Net income	223,110						223,110
Unrealized gain (loss) on investment in available for sale securities	55,106
Unrealized gain on investment in available for sale securities	62,972							62,972
Unrealized loss on investment in available for sale securities	(7,866)							(7,866)
Issuance of shares, net	371,956			$ 127		371,829
Issuance of shares, net (in shares)				12,650,000
Common share grants	2,547			$ 1		2,546
Share grants (in shares)				91,600
Common share repurchases	(613)					(613)
Common share repurchases (in shares)				(20,689)
Distributions	(334,799)		(20,664)		(314,135)
Distribution to common shareholders of The RMR Group Inc. common stock	0
Balance at Dec. 31, 2016	$ 3,129,389	$ 208,107	$ (341,977)	$ 1,643	$ (4,494,407)	$ 4,539,673	$ 3,104,767	$ 39,583
Balance (in shares) at Dec. 31, 2016		11,600,000		164,268,199