Fair Value of Assets and Liabilities - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 31, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($) Tenant	Aug. 06, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jul. 31, 2014 USD ($) $ / shares	Jun. 30, 2014 USD ($)	Dec. 31, 2013 USD ($)
Fair value of assets and liabilities
Fair value of derivative liability					$ (9,300)	$ (6,700)
Number of tenants responsible for more than 3% of total annualized rents | Tenant			0
Cash and cash equivalents			$ 1,286,902			$ 364,516		$ 420,664	$ 217,032
Subsequent event | Australia Subsidiary
Fair value of assets and liabilities
Cash and cash equivalents				$ 7,000
Subsequent event | Forecast
Fair value of assets and liabilities
Foreign currency exchange loss		$ 9,500
Australia Subsidiary | Subsequent event
Fair value of assets and liabilities
Transfer of US Dollars from Australian Subsidiary	$ 218,000
Total rents | Credit concentration
Fair value of assets and liabilities
Concentration risk			3.00%
Related/Corvex
Fair value of assets and liabilities
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							$ 8,400
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							$ 8,400
Minimum
Fair value of assets and liabilities
Price per common share during one year period after date (in dollars per share) | $ / shares							$ 26.00
Price per common share during first and second year after date (in dollars per share) | $ / shares							$ 26.00
Minimum | Subsequent event
Fair value of assets and liabilities
Price per common share during one year period after date (in dollars per share) | $ / shares	$ 26.00