Related Party Transactions (Schedule of Fees Earned from Related Parties) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Management Fees [Member]
Revenue from related party transactions	$ 2,456	$ 2,731
Leasing Fees [Member]
Revenue from related party transactions	555	1,294
Construction and Development Fees [Member]
Revenue from related party transactions	$ 1,067	$ 843

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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