Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 258,460	$ 242,944	$ 231,113	$ 283,658	$ 288,733	$ 282,276	$ 275,872	$ 286,257	$ 1,016,175	$ 1,133,138	$ 1,120,975
Net (loss) income attributable to common stockholders	38,487	12,688	19,046	(25,332)	40,291	56,965	51,728	90,446	$ 44,889	$ 239,430	$ 249,127
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Nonredeemable	174	57	87	(115)	178	157	109	190
Net income attributable to common unit holders	$ 38,661	$ 12,745	$ 19,133	$ (25,447)	$ 40,469	$ 57,122	$ 51,837	$ 90,636
Income per common share - basic (note 15)	$ 0.23	$ 0.07	$ 0.11	$ (0.15)	$ 0.24	$ 0.34	$ 0.31	$ 0.54	$ 0.27	$ 1.43	$ 1.47
Income per common share - diluted (note 15)	$ 0.23	$ 0.07	$ 0.11	$ (0.15)	$ 0.24	$ 0.34	$ 0.31	$ 0.54	$ 0.26	$ 1.43	$ 1.46