Description of Business (Narrative) (Details) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Jun. 30, 2015 USD ($)	Dec. 31, 2013 USD ($)	Sep. 30, 2015 property $ / shares shares	Dec. 31, 2014 $ / shares shares	Oct. 15, 2013 $ / shares shares
Organization And Description Of Business [Line Items]
Number of properties | property			25
Common stock, par value			$ 0.01	$ 0.01
Common stock, shares issued | shares			41,101,507	29,408,138
Net proceeds from issuance of shares | $		$ 279.0
Ownership interest			85.70%
Common Class A [Member]
Organization And Description Of Business [Line Items]
Common stock, par value					$ 0.01
Common stock, shares issued | shares					14,087,500
Net proceeds from issuance of shares | $	$ 203.4