Earnings Per Share - Reconciliation of Net Income (Loss) and Number of Common Shares Used in Computations of "Basic" EPS and "Diluted" EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 36,590	$ 101,825	$ 116,105
Income attributable to non-controlling interests	(869)	(1,126)	(1,671)
Write-off of preferred share original issuance costs	0	(7,176)	0
Preferred dividends	(20,531)	(32,231)	(33,531)
Earnings attributable to unvested shares and OP Units	(204)	(687)	(1,137)
Net income attributable to common shareholders after allocation to participating securities	$ 14,986	$ 60,605	$ 79,766
Denominators – Number of Shares
Basic – Average shares outstanding	193,336	183,026	184,528
Assumed conversion of dilutive securities	441	228	7
Diluted – Average shares outstanding	193,777	183,254	184,535
Earnings Per Share:
Basic	$ 0.08	$ 0.33	$ 0.43
Diluted	$ 0.08	$ 0.33	$ 0.43