Investments in real estate, net Schedule of investment in real estates (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Real Estate Properties [Line Items]
Rental properties	$ 6,849,966	$ 6,442,208
Land/future value-added projects:
Land available for development	716,349	658,546
Real Estate Investment Property, at Cost	8,166,631	7,682,376
Less: accumulated depreciation	(1,083,169)	(952,106)
Equity Method Investments	114,168	46,644
Investments in real estate, net	7,197,630	6,776,914
Construction in progress ("CIP")/current value-added projects:
Construction in progress ("CIP")/current value-added projects:
Development in process	600,316	581,622
Active development in North America \| North America [Member]
Construction in progress ("CIP")/current value-added projects:
Development in process	532,053	511,838
Active redevelopment in North America \| North America [Member]
Construction in progress ("CIP")/current value-added projects:
Development in process	32,661	8,856
Active development and redevelopment in Asia \| Asia [Member]
Construction in progress ("CIP")/current value-added projects:
Development in process	35,602	60,928
Land undergoing predevelopment activities (CIP) in North America (2)
Land/future value-added projects:
Land available for development	404,222	382,289
Land held for future development in North America
Land/future value-added projects:
Land available for development	299,891	253,314
Land held for future development in North America \| North America [Member]
Land/future value-added projects:
Land available for development	221,572	176,063
Land held for future development in North America \| Asia [Member]
Land/future value-added projects:
Land available for development	78,319	77,251
Land subject to sale negotiations
Land/future value-added projects:
Land available for development	12,236	22,943
50, 60, and 100 Binney Street Project [Member] \| Land undergoing predevelopment activities (CIP) in North America (2) \| North America [Member]
Land/future value-added projects:
Land available for development	313,379	284,672
Other Projects in North America [Member] \| Land undergoing predevelopment activities (CIP) in North America (2) \| North America [Member]
Land/future value-added projects:
Land available for development	$ 90,843	$ 97,617

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The current amount of expenditures for a real estate project that has not yet been completed.

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Carrying amount of land available for development.

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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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Carrying amount of income producing properties held for rental.

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