Schedule of Unaudited Proforma Results of Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Abstract]
Total revenues		$ 379,145	$ 348,684	$ 307,552
Net loss	[1]	$ (31,708)	$ (70,864)	$ (62,071)
Loss per share of common stock (basic and diluted)		$ (0.18)	$ (0.42)	$ (0.42)
Weighted average number of shares of common stock outstanding (basic and diluted)	[2]	175,121	170,735	148,443

[1] Net loss for the years ended December 31, 2016 and 2015 was adjusted to exclude approximately $0.7 million and $11.3 million, respectively, of acquisition related expenses directly attributable to the properties acquired during the years ended December 31, 2016 and 2015. The unaudited pro forma results for the years ended December 31, 2015 and 2014 were adjusted to include these charges as if the properties were acquired on January 1, 2015 and 2014, respectively.

[2] As a result of the properties acquired in 2015 being treated as operational since January 1, 2014, the Company assumed approximately 31.6 million additional shares were issued as of January 1, 2014. Consequently, the weighted average number of shares outstanding was adjusted to reflect this amount of shares being issued as of January 1, 2014, instead of actual dates on which the shares were issued, and such shares were treated as outstanding as of the beginning of the period presented. The property acquired in 2016 was assumed to be funded with cash on hand as of December 31, 2014.