Earnings Per Share - Computation of Company's Earnings Per Share (EPS) and Reconciliation of Net (Loss) Income from Continuing Operations and Number of Common Shares Used in Computations of "Basic" EPS and "Diluted" EPS (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Loss from continuing operations	$ (63,908)	$ (92,155)
Plus: Gain on disposition of real estate	10,011	38,127
Income attributable to non-controlling interests, net	(256)	(213)
Less: Preferred dividends	(8,383)	(5,594)
Less: Earnings attributable to unvested shares and operating partnership units	(203)	(251)
Net loss attributable to common shareholders after allocation to participating securities	$ (62,739)	$ (60,086)
Denominators – Number of Shares
Basic and Diluted—Average shares outstanding	369,120	366,430
Loss Per Share:
Basic	$ (0.17)	$ (0.16)
Diluted	$ (0.17)	$ (0.16)