Fair Value Measurements - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Carrying value
Fair value of financial assets and liabilities
Mortgages payable assumed in connection with acquisitions	$ 201.0	$ 822.4
Notes and bonds payable	22,002.1	18,562.1
Fair value
Fair value of financial assets and liabilities
Mortgages payable assumed in connection with acquisitions	194.6	814.5
Notes and bonds payable	20,580.5	17,603.7
Mortgages payable:
Fair value of financial assets and liabilities
Unamortized net discounts	0.5	0.4
Deferred financing costs	0.4	0.4
Notes and bonds payable
Fair value of financial assets and liabilities
Unamortized net discounts	159.4
Unamortized net premiums		125.3
Deferred financing costs	93.1	83.8
Basis adjustment on interest rate swap designated as fair value hedge	$ (1.6)	$ (1.3)

Amount, after accumulated amortization, of debt discount.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
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- Definition

Amount, after accumulated amortization, of debt premium.

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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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.

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Net fair value of all derivative instruments designated as fair value hedging instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Fair value portion of contractual obligation to pay money on demand or on fixed or determinable dates.

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- Definition

Fair value portion of notes payable.

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