This element represents the amortization of deferred leasing fees incurred by the lessor and amortized over the term of the lease. Such fees represent (a) costs to originate a lease incurred in transactions with independent third parties that (i) result directly from and are essential to acquire that lease and (ii) would not have been incurred had that leasing transaction not occurred and (b) certain costs directly related to specified activities performed by the lessor for that lease. Those activities are: evaluating the prospective lessee's financial condition; evaluating and recording guarantees, collateral, and other security arrangements; negotiating lease terms; preparing and processing lease documents; and closing the transaction.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=6748888&loc=d3e40246-112709

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Name:	us-gaap_AmortizationOfDeferredLeasingFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 29.2	$ 22.6	$ 57.0	$ 44.5
Amortization of direct lease acquisition costs	$ 9.2	$ 8.4	$ 16.7	$ 15.4
Minimum
Finite-Lived Intangible Assets [Line Items]
Direct lease acquisition costs, useful life			28 days
Maximum
Finite-Lived Intangible Assets [Line Items]
Direct lease acquisition costs, useful life			1 year