Equity - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator - Basic:
Net income	$ 19,145	$ 16,705
Private perpetual preferred unit distributions	(234)	(234)
Net income attributable to non-controlling interests	(8,926)	(9,043)
Earnings allocated to unvested shares	(7)	(8)
Net income attributable to common stockholders - basic	9,978	7,420
Numerator - Diluted:
Net income	19,145	16,705
Private perpetual preferred unit distributions	(234)	(234)
Earnings allocated to unvested shares	(7)	(172)
Net income attributable to common stockholders - diluted	$ 18,904	$ 16,299
Denominator:
Weighted average shares outstanding - basic (in shares)	156,493,000	120,778,000
Operating partnership units (in shares)	139,895,000	145,356,000
Effect of dilutive securities:
Stock-based compensation plans (in shares)	775,000	507,000
Exchangeable senior notes (in shares)	799,000	0
Weighted average shares outstanding - diluted (in shares)	297,962,000	266,641,000
Earnings per share:
Basic (in USD per share)	$ 0.06	$ 0.06
Diluted (in USD per share)	$ 0.06	$ 0.06
Antidilutive securities (in shares)	622,565	0