Organization and Description of Business (Narrative) (Details)	Sep. 30, 2016 property
Organization and Description of Business [Line Items]
Number of properties	144
Common Interest
Organization and Description of Business [Line Items]
Ownership percentage in the Operating Partnership	98.40%
Preferred Interest
Organization and Description of Business [Line Items]
Ownership percentage in the Operating Partnership	100.00%
North America
Organization and Description of Business [Line Items]
Number of properties	106
Europe
Organization and Description of Business [Line Items]
Number of properties	31
Australia
Organization and Description of Business [Line Items]
Number of properties	3
Asia
Organization and Description of Business [Line Items]
Number of properties	4
Unconsolidated Properties
Organization and Description of Business [Line Items]
Number of properties	14