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, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
(Loss) income from continuing operations	$ (92,155)	$ 33,492
Plus: Gain on disposition of real estate	38,127	12,381
Income attributable to non-controlling interests, net	(213)	(300)
Less: Preferred dividends	(5,594)	(5,594)
Less: Earnings attributable to unvested shares and operating partnership units	(251)	(210)
Net (loss) income attributable to common shareholders after allocation to participating securities	$ (60,086)	$ 39,769
Denominators – Number of Shares
Basic—Average shares outstanding	366,430	364,691
Effect of dilutive securities—Stock options	0	351
Diluted—Average shares outstanding	366,430	365,042
(Loss) Earnings Per Share:
Basic	$ (0.16)	$ 0.11
Diluted	$ (0.16)	$ 0.11