Real Estate Investments Gross Carrying Value of Company's Properties (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Property, Plant and Equipment, Gross [Abstract]
Land	$ 664,952	$ 662,107
Buildings and Improvements, Gross	3,465,544	3,576,065
Leasehold Improvements, Gross	501,414	487,997
Real Estate Investments	$ 4,631,910	$ 4,726,169

Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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Amount before accumulated depreciation of additions or improvements to assets held under a lease arrangement.

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Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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