v3.21.2

Unsecured Credit Agreements - Summary of Unsecured Credit Agreements (Parenthetical) (Detail) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2021 | Dec. 31, 2020
1 Month LIBOR | Revolving Credit Facilities |  |
Debt Instrument [Line Items] |  |
Interest rate | 1.00% |
Daily LIBOR | Revolving Credit Facilities |  |
Debt Instrument [Line Items] |  |
Interest rate | 1.00% |
Unsecured Debt | 1 Month LIBOR |  |
Debt Instrument [Line Items] |  |
Interest rate | 0.08% | 0.14%
Unsecured Debt | 1 Month LIBOR | 2022 Unsecured Term Loan |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate | 1.00% | 1.25%
Unsecured Debt | 1 Month LIBOR | 2024 Unsecured Term Loan |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate | 1.00% | 1.25%
Unsecured Debt | 1 Month LIBOR | 2023 Unsecured Term Loan |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate | 1.10% | 1.35%
Unsecured Debt | 1 Month LIBOR | 2026 Unsecured Term Loan |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate | 1.00% | 1.85%
Unsecured Debt | 1 Month LIBOR | Revolving Credit Facilities |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate |  | 1.20%
Unsecured Debt | Daily LIBOR |  |
Debt Instrument [Line Items] |  |
Interest rate | 0.07% |

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