Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
BASIC
Income from continuing operations attributable to common shareholders - basic	$ 47,659	$ 16,158	$ 77,818	$ 15,179
Income (loss) from discontinued operations attributable to common shareholders - basic	(5)	(3,416)	1,682	(3,275)
Net income attributable to common shareholders	$ 47,654	$ 12,742	$ 79,500	$ 11,904
Weighted-average common shares outstanding - basic	233,812,062	228,368,053	233,172,422	227,765,718
Income from continuing operations (in USD per share)	$ 0.20	$ 0.07	$ 0.33	$ 0.07
Income (loss) from discontinued operations (in USD per share)	0.00	(0.02)	0.01	(0.02)
Net income attributable to common shareholders (USD per share)	$ 0.20	$ 0.05	$ 0.34	$ 0.05
DILUTED
Income from continuing operations attributable to common shareholders - basic	$ 47,659	$ 16,158	$ 77,818	$ 15,179
Impact of assumed conversions	764	0	1,633	0
Income from continuing operations attributable to common shareholders	48,423	16,158	79,451	15,179
Income (loss) from discontinued operations attributable to common shareholders - basic	(5)	(3,416)	1,682	(3,275)
Impact of assumed conversions	0	0	0	0
Income (loss) from discontinued operations attributable to common shareholders	(5)	(3,416)	1,682	(3,275)
Net income attributable to common shareholders	$ 48,418	$ 12,742	$ 81,133	$ 11,904
Effect of dilutive securities:
Share options (in shares)	296,501	483,131	369,079	509,890
6.00% Convertible Guaranteed Notes (in shares)	1,941,833	0	2,165,367	0
Operating Partnership Units (in shares)	3,852,974	0	3,852,974	0
Weighted-average common shares outstanding (in shares)	239,903,370	228,851,184	239,559,842	228,275,608
Income (loss) per common share:
Income from continuing operations (USD per share)	$ 0.20	$ 0.07	$ 0.33	$ 0.07
Income (loss) from discontinued operations (USD per share)	0.00	(0.02)	0.01	(0.02)
Net income (loss) attributable to common shareholders (USD per share)	$ 0.20	$ 0.05	$ 0.34	$ 0.05
Convertible Debt [Member] | 6% Convertible Guaranteed Note [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stated interest rate	6.00%		6.00%