Real Estate Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Assets
Gross historical cost	$ 1,402,884	$ 1,350,585
Accumulated amortization	(966,714)	(881,096)
Net book value	$ 436,170	$ 469,489
Weighted-average amortization period in years	13 years 8 months	13 years 5 months
Liabilities
Gross historical cost	$ 97,575	$ 100,996
Accumulated amortization	(52,134)	(46,048)
Net book value	$ 45,441	$ 54,948
Weighted-average amortization period in years	15 years 2 months	14 years 6 months
In place lease intangibles [Member]
Assets
Gross historical cost	$ 1,252,143	$ 1,179,537
Above market tenant leases [Member]
Assets
Gross historical cost	61,700	67,529
Below market ground leases [Member]
Assets
Gross historical cost	61,628	80,224
Lease commissions [Member]
Assets
Gross historical cost	27,413	23,295
Gross historical cost [Member]
Assets
Gross historical cost	1,402,884	1,350,585
Below market tenant leases [Member]
Liabilities
Gross historical cost	89,468	93,089
Above market ground leases [Member]
Liabilities
Gross historical cost	$ 8,107	$ 7,907

Real Estate Intangible Liabilities Accumulated Amortization.

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- Definition

Real Estate Intangible Liabilities Gross.

+ References

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- Definition

Real Estate Intangible Liabilities Net.

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- Definition

Real Estate Intangible Liabilities Weighted Average Useful Life.

+ References

No definition available.

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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- Definition

Amount before accumulated amortization of finite-lived intangible assets classified as other.

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