Leases - Tenant Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractual Rent Adjustment To Rental Income Resulting From Lease Collectibility Assessment	$ 0.3	$ 0.6	$ 1.7	$ 0.6
Contractual Rent Adjustment To Rental Income	(0.1)		(1.3)
Accrued Rent Adjustment To Rental Income Resulting From Lease Collectibility Assessment	0.0	1.2	(0.1)	0.9
Lease Security Deposits Available in Letters of Credit	29.8		29.8		$ 30.1
Lease security deposits in restricted cash	0.7		0.7		0.7
Lease security deposits included in tenant prepaid rent and security deposits on the Balance Sheet	11.6		11.6		11.0
Real Estate Taxes, Tenant Responsibility	5.3	$ 4.9	10.4	$ 9.7
Accrued Income Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred Rent Receivables, Net	$ 68.7		$ 68.7		$ 60.0

Accrued Rent Adjustment To Rental Income Resulting From Lease Collectibility Assessment

No definition available.

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- Definition

Contractual Rent Adjustment To Rental Income

+ References

No definition available.

+ Details

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- Definition

Contractual Rent Adjustment To Rental Income Resulting From Lease Collectibility Assessment

+ References

No definition available.

+ Details

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- Definition

Represents the amount of lease security deposit for the benefit of the entity, available in letters of credit.

+ References

No definition available.

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- Definition

Real Estate Taxes, Tenant Responsibility

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property, by the lessor or lessee, respectively. Such receivable is reduced by allowances attributable to, for instance, credit risk associated with a lessee.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 35
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- Definition

The amount of an asset, typically cash, provided to a counterparty to provide certain assurance of performance by the entity pursuant to the terms of a written or oral agreement, such as a lease.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

This element represents money paid in advance to protect the provider of a product or service, such as a lessor, against damage or nonpayment by the buyer or tenant (lessee) during the term of the agreement. Such damages may include physical damage to the property, theft of property, and other contractual breaches. Security deposits held may be interest or noninterest bearing.

+ References

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-Publisher FASB
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