Equity - Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:
Net income	$ 22,734	$ 2,281	$ 59,246	$ 7,282
Private perpetual preferred unit distributions	(241)		(241)
Net income attributable to non-controlling interests	14,171		36,480
Earnings allocated to unvested shares	(8)		(27)
Net income attributable to common stockholders - basic	8,314		22,498
Earnings allocated to unvested shares and LTIP units	(127)		(374)
Net income attributable to common stockholders - diluted	$ 22,366		$ 58,631
Denominator:
Weighted average shares outstanding - basic	97,729,000		96,226,000
Operating partnership units	165,312,000		154,470,000
Weighted average shares outstanding - diluted	263,041,000		250,696,000
Basic	$ 0.09		$ 0.23
Diluted	$ 0.09		$ 0.23
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	674,642		607,654