Shareholders' Equity - Additional Information (Details) $ / shares in Units, $ in Thousands	Aug. 03, 2017 USD ($)	Jul. 28, 2017 shares	Jul. 12, 2017 USD ($) $ / shares	Jul. 05, 2017 $ / shares shares	Jun. 30, 2017 $ / shares shares	May 22, 2017 USD ($) $ / shares	May 17, 2017 USD ($) trustee $ / shares shares	Feb. 23, 2017 USD ($) $ / shares
Distributions
Cash distribution to common shareholders (in dollars per share) | $ / shares						$ 0.43		$ 0.43
Distribution paid to common shareholders | $						$ 30,606		$ 30,606
Number of trustees | trustee							6
Shares withheld for tax withholding (in shares) | shares							450
Value of shares withheld for tax withholding | $							$ 10
Subsequent Event
Distributions
Distribution paid to common shareholders | $			$ 41,364
Distribution payable to common shareholders (in dollars per share) | $ / shares			$ 0.43
Common shares | Trustees
Distributions
Shares granted to each trustee (in shares) | shares							3,000
Value of shares granted (in dollars per share) | $ / shares							$ 21.75
Underwritten Public Offering | Subsequent Event
Distributions
Number of shares sold in offering (in shares) | shares				25,000,000
Price per share in offering (in dollars per share) | $ / shares				$ 18.50
Over-Allotment Option | Subsequent Event
Distributions
Number of shares sold in offering (in shares) | shares		2,907,029
Price per share in offering (in dollars per share) | $ / shares				$ 18.50
Additional number of shares available (in shares) | shares				3,750,000
Former Employee of RMR LLC
Distributions
Stock repurchased to satisfy tax withholding obligation (in shares) | shares					278
Stock repurchased to satisfy tax withholding obligation (in dollars per share) | $ / shares					$ 18.31
Forecast | Underwritten Public Offering
Distributions
Proceeds from offering | $	$ 493,838