Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Detail) $ in Thousands	Sep. 30, 2020 USD ($)
Debt Instrument [Line Items]
Payables due 2020	$ 106
Payables due 2021	103,122
Payables due 2022	394
Payables due 2023	7,403
Payables due 2024	197,978
Payables due Thereafter	2,000,349
Debt obligations	2,309,352
Term Note - Fixed Rate 5.54% [Member]
Debt Instrument [Line Items]
Payables due 2021	100,000
Debt obligations	100,000
Term note, fair value	104,332
Term Note - Fixed Rate 4.533% [Member]
Debt Instrument [Line Items]
Payables due 2024	175,000
Debt obligations	175,000
Term note, fair value	197,640
Term Note - Fixed Rate 3.50% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	600,000
Debt obligations	600,000
Term note, fair value	674,845
Term Note - Fixed Rate 3.875% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	450,000
Debt obligations	450,000
Term note, fair value	514,557
Term Note - Fixed Rate 3.67% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	200,000
Debt obligations	200,000
Term note, fair value	224,265
Term Note - Fixed Rate 4.00% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	350,000
Debt obligations	350,000
Term note, fair value	399,957
Term Note - Fixed Rate 2.20% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	400,000
Debt obligations	400,000
Term note, fair value	398,566
Mortgage Note - Fixed Rate 4.98% [Member]
Debt Instrument [Line Items]
Payables due 2020	15
Payables due 2021	2,748
Debt obligations	2,763
Debt instrument, fair value	2,769
Mortgage Note - Fixed Rate 4.065% [Member]
Debt Instrument [Line Items]
Payables due 2020	26
Payables due 2021	104
Payables due 2022	108
Payables due 2023	3,620
Debt obligations	3,858
Debt instrument, fair value	3,826
Mortgage Note - Fixed Rate 5.26% [Member]
Debt Instrument [Line Items]
Payables due 2020	19
Payables due 2021	78
Payables due 2022	83
Payables due 2023	3,567
Debt obligations	3,747
Debt instrument, fair value	3,839
Mortgage Note - Fixed Rate 4.4625% [Member]
Debt Instrument [Line Items]
Payables due 2024	22,749
Debt obligations	22,749
Debt instrument, fair value	21,619
Mortgage Note - Fixed Rate 5.99% [Member]
Debt Instrument [Line Items]
Payables due 2020	46
Payables due 2021	192
Payables due 2022	203
Payables due 2023	216
Payables due 2024	229
Payables due Thereafter	349
Debt obligations	1,235
Debt instrument, fair value	$ 1,286

Long term debt maturities repayments of principal after year four.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Fair value portion of notes payable.

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