Organization and Business (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Jan. 21, 2015	Aug. 19, 2014	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Organization and Business
Common stock, shares authorized			500,000,000		500,000,000	500,000,000
Common stock, par value (in dollars per share)			$ 0.01		$ 0.01	$ 0.01
Organization and Business
Shares issued upon exercise of the underwriters' overallotment option	2,475,000
Number of partnership units issued	18,975,000
Common shares sold	18,975,000
Units
Organization and Business
Net proceeds	$ 297,300
ATM Program | Operating Partnership
Organization and Business
Common shares sold			1,007,695	247,397	1,255,092
Weighted average price			$ 16.56	$ 16.96	$ 16.63
Net proceeds			$ 16,438	$ 4,140	$ 20,578
ATM Program | Maximum
Organization and Business
Aggregate offering price of common stock		$ 150,000