Related Person Transactions - Narrative (Details) $ / shares in Units, $ in Millions							1 Months Ended	5 Months Ended	6 Months Ended	12 Months Ended
	Nov. 02, 2015 USD ($)	Jul. 20, 2015 option	May 04, 2015 USD ($)	Mar. 01, 2015 USD ($)	Jul. 31, 2014 USD ($) option $ / shares	Jun. 01, 2014 USD ($) parking_space	Aug. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2014 USD ($)
Related Party Transaction [Line Items]
Lease termination period duration									30 days
Minimum
Related Party Transaction [Line Items]
Average closing price per common share during one year period after date (at least) (in dollars per share) | $ / shares					$ 26.00
Average closing price per common share during first and second year after date (in dollars per share) | $ / shares					$ 26.00
Equity Group Investments and associated entities
Related Party Transaction [Line Items]
Lease term		5 years			7 months
Number of renewal options of lease arrangement | option		1			1
Renewal term of lease arrangement		5 years			3 months
Annual lease payment, year one									$ 0.5
Tenant Improvements									0.7
Term of license agreement						1 year
License fee	$ 0.1		$ 0.1			$ 0.2
Number of parking spaces | parking_space						1
Lease payment, initial term					$ 0.2
Lease payment	$ 0.1		$ 0.2
Equity Group Investments and associated entities | Minimum
Related Party Transaction [Line Items]
Annual lease payment after year one									0.8
Equity Group Investments and associated entities | Maximum
Related Party Transaction [Line Items]
Annual lease payment after year one									$ 0.9
Related/Corvex
Related Party Transaction [Line Items]
Due to related persons					33.5
Amount of reimbursements payable to related party upon the approval of shareholders							$ 8.4			$ 16.7
Amount of reimbursements payable to related party if specified minimum common share price maintain during the one year period after the date on which the reimbursement is approved by shareholders					8.4
Amount of reimbursements payable to related party if specified minimum common share price maintain during the one year period between the first and second anniversaries of the date on which the reimbursement is approved by shareholders					$ 8.4
RMR and RMR Australia
Related Party Transaction [Line Items]
Monthly management transition fee				$ 0.1				$ 1.2