Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
BASIC
Net income attributable to common shareholders	$ 40,397	$ 47,781
Weighted-average number of common shares outstanding - basic	237,179,526	232,642,803
Income (loss) per common share:
Net income attributable to common shares outstanding - basic (in dollars per share)	$ 0.17	$ 0.21
DILUTED
Impact of assumed conversions	$ (19)	$ 1,046
Net income attributable to common shareholders	$ 40,378	$ 48,827
Effect of dilutive securities:
Share options (in shares)	136,881	132,191
6.00% Convertible Guaranteed Notes (in shares)	0	1,941,237
OP Units (in shares)	3,771,642	3,820,192
Nonvested common shares (in shares)	0	348,748
Weighted-average common shares outstanding (in shares)	241,088,049	238,885,171
Income (loss) per common share:
Net income attributable to common shareholders - per common share diluted (in dollars per share)	$ 0.17	$ 0.20
6% Convertible Guaranteed Note [Member]
Debt Instrument [Line Items]
Stated interest rate		6.00%