Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
BASIC
Net income attributable to common shareholders	$ 5,519	$ 53,875	$ 45,916	$ 101,655
Weighted-average number of common shares outstanding - basic	237,720,198	232,592,998	237,451,355	232,617,901
Income (loss) per common share:
Net income attributable to common shares outstanding - basic (in dollars per share)	$ 0.02	$ 0.23	$ 0.19	$ 0.44
DILUTED
Impact of assumed conversions	$ 0	$ 315	$ (19)	$ 628
Net income attributable to common shareholders	$ 5,519	$ 54,190	$ 45,897	$ 102,283
Effect of dilutive securities:
Share options (in shares)	86,653	273,920	111,252	204,783
6.00% Convertible Guaranteed Notes (in shares)	0	1,878,445	0	1,909,841
OP Units (in shares)	3,724,462	0	3,747,922	0
Nonvested common shares (in shares)	0	481,836	0	418,731
Weighted-average common shares outstanding (in shares)	241,531,313	235,227,199	241,310,529	235,151,256
Income (loss) per common share:
Net income attributable to common shareholders - per common share diluted (in dollars per share)	$ 0.02	$ 0.23	$ 0.19	$ 0.43
6% Convertible Guaranteed Note [Member]
Debt Instrument [Line Items]
Stated interest rate		6.00%		6.00%