Real Estate Activities (Investments in Real Estate) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Real Estate [Abstract]
Buildings, improvements and construction in progress	$ 2,843,326	$ 3,049,758
Land, including land held for development	442,078us-gaap_LandAndLandImprovements	478,110us-gaap_LandAndLandImprovements
Total investments in real estate	3,285,404	3,527,868
Accumulated depreciation	(1,061,051)	(1,012,746)
Net investments in real estate	$ 2,224,353us-gaap_RealEstateInvestmentPropertyNet	$ 2,515,122us-gaap_RealEstateInvestmentPropertyNet

Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

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- Definition

Amount before accumulated deprecation and depletion of real estate held for productive use and additions or improvements to real estate held for productive use, examples include, but are not limited to, walkways, driveways, fences, and parking lots. Excludes land held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6812-107765

+ Details

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- Details

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- Definition

The cumulative amount of depreciation for real estate property held for investment purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(3))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 7

+ Details

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- Definition

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.

+ References

+ Details

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- Definition

Amount of real estate investment property, net of accumulated depreciation, 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.

+ References

+ Details

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