Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	Dec. 14, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues		$ 467,440	$ 511,886	$ 507,066	$ 435,512	$ 430,533	$ 459,639	$ 451,900	$ 394,250	$ 1,921,904	$ 1,736,322	$ 1,563,855
Net income		(19,494)	61,185	83,146	41,581	56,523	49,197	53,915	37,550	166,418	197,185	133,178
Net income available for common shareholders		$ (24,660)	$ 56,019	$ 77,980	$ 36,415	$ 51,357	$ 44,031	$ 48,749	$ 32,384	$ 145,754	$ 176,521	$ 100,992
Net income available for common shareholders per share (basic and diluted)		$ (0.16)	$ 0.37	$ 0.52	$ 0.24	$ 0.34	$ 0.29	$ 0.33	$ 0.22	$ 0.97	$ 1.18	$ 0.73
Distributions per common share			$ 0.50	$ 0.50	$ 0.49
Distributions per common share		0.70				$ 0.49	$ 0.49	$ 0.49	$ 0.48
RMR Inc
Non cash distributions per common share	$ 0.1974	$ 0.1974