Acquired Intangible Assets and Liabilities - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Customer Relationship Value, Acquired In-Place Lease Value and Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Amortization of customer relationship value, acquired in-place lease value and deferred leasing costs	$ 65.2	$ 75.1	$ 199.3	$ 210.9
Rental and other services \| Below-Market Leases, Net of Above-Market Leases
Finite-Lived Intangible Assets [Line Items]
Decrease in revenue	$ (0.7)	$ (2.4)	$ (3.3)	$ (8.7)

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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