Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
BASIC
Net income (loss) attributable to common shareholders	$ (3,327)	$ 5,519	$ (19,284)	$ 45,916
Weighted-average number of common shares outstanding - basic	237,312,726	237,720,198	237,690,306	237,451,355
Income (loss) per common share:
Net income (loss) attributable to common shares outstanding - basic (in dollars per share)	$ (0.01)	$ 0.02	$ (0.08)	$ 0.19
DILUTED
Impact of assumed conversions	$ 0	$ 0	$ 0	$ (19)
Net income (loss) attributable to common shareholders	$ (3,327)	$ 5,519	$ (19,284)	$ 45,897
Effect of dilutive securities:
Share options (in shares)	0	86,653	0	111,252
OP Units (in shares)	0	3,724,462	0	3,747,922
Weighted-average common shares outstanding (in shares)	237,312,726	241,531,313	237,690,306	241,310,529
Income (loss) per common share:
Net income (loss) attributable to common shareholders - per common share diluted (in dollars per share)	$ (0.01)	$ 0.02	$ (0.08)	$ 0.19

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