Borrowings - Summary of Outstanding Debt (Details) $ in Thousands	9 Months Ended
Sep. 30, 2021 USD ($)
Debt Instrument [Line Items]
Total Outstanding Debt	$ 4,540,887
Debt Instrument, Interest Rate, Effective Percentage	3.40%
Fixed Rate Property Mortgages [Member]
Debt Instrument [Line Items]
Contract Maturity	Sep. 17, 2048
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	$ 4,175,256
Debt Instrument, Interest Rate, Effective Percentage	3.30%
Unsecured Debt [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 4,175,000
Debt Instrument, Interest Rate, Effective Percentage	3.30%
Contract Maturity	Mar. 04, 2029
Unsecured Debt [Member] \| Commercial Paper Notes [Member] \| Variable Rate Commercial Paper Program [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 25,000
Debt Instrument, Interest Rate, Effective Percentage	0.20%
Contract Maturity	Oct. 01, 2021
Unsecured Debt [Member] \| $1 billion unsecured revolving credit facility [Member] \| Fair Market Value Adjustment and Debt Issuance Cost [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ (24,744)
Secured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	365,631
Debt issuance costs	$ (3,261)
Debt Instrument, Interest Rate, Effective Percentage	4.40%
Secured Debt [Member] \| Fixed Rate Property Mortgages [Member]
Debt Instrument [Line Items]
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate	$ 368,892
Secured Debt [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate	$ 368,900
Debt Instrument, Interest Rate, Effective Percentage	4.40%
Contract Maturity	Dec. 31, 2048

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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