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.

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=7658586&loc=d3e16265-109275

+ Details

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- Definition

Amount of non-cash amortization of intangible asset (liability) for above and below market leases.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	duration

- Definition

The amount of capitalized costs incurred in the period to renew or extend the term of a recognized finite-lived (amortizing and amortizable) intangible asset.

+ 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 (d)(1)

-URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS142-3

-Paragraph c

-Subparagraph d(1)

-Appendix A1

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

Weighted average period before the next renewal or extension (both explicit and implicit) for intangible assets that have been renewed or extended, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

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Acquired Intangible Assets And Liabilities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired below-market lease value, net of acquired above-market lease value	$ 3.0	$ 2.9	$ 6.1	$ 5.1
Acquired Below-Market Lease Value [Member]
Finite-Lived Intangible Assets [Line Items]
Expected remaining lives			6 years 8 months 12 days
Acquired Above-Market Lease Value [Member]
Finite-Lived Intangible Assets [Line Items]
Expected remaining lives			4 years 10 months 24 days
Acquired In Place Lease Value [Member]
Finite-Lived Intangible Assets [Line Items]
Costs incurred to renew or extend leases	$ 15.4	$ 12.4	$ 30.3	$ 24.3
Expected remaining lives			6 years 10 months 24 days
Weighted average period prior to renewal (years)			5 years 6 months