v3.21.2

Unsecured Credit Agreements - Additional Information (Detail) - USD ($) $ in Thousands |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Sep. 15, 2021 | Mar. 12, 2021 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total unsecured debt |  |  | $ 1,597,868 |  | $ 1,597,868 |  | $ 1,547,667
Debt Instrument, Interest Rate, Stated Percentage |  |  | 5.00% |  | 5.00% |  |
Cost of debt extinguishment |  |  | $ (242) | $ (392) | $ (368) | $ (414) |
Other Nonoperating Income (Expense) |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Cost of debt extinguishment |  |  | 214 | 392 | 340 | 392 |
Revolving Credit Facility [Member] |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Unamortized debt issuance costs |  |  |  | 5,918 |  | 5,918 |
2026 Unsecured Term Loan |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Paydown amount |  | $ 50,000 |  |  |  |  |
Debt issuance costs incurred |  |  | 4,069 |  | 5,020 |  |
2026 Unsecured Term Loan | LIBOR |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Basis spread on variable rate |  | 1.00% |  |  |  |  | 1.60%
2026 Unsecured Term Loan | LIBOR | Minimum |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Basis spread on variable rate |  | 0.85% |  |  |  |  | 1.45%
2026 Unsecured Term Loan | LIBOR | Maximum |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Basis spread on variable rate |  | 1.65% |  |  |  |  | 2.40%
Modification of Existing Debt |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Debt issuance costs incurred |  |  |  | $ 5,918 |  | $ 5,918 |
Unamortized debt issuance costs |  |  | $ 3,379 |  | $ 4,325 |  |
2031 Senior Unsecured Public Notes |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total unsecured debt | $ 375,000 |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 2.60% |  |  |  |  |  |
Rate of Principal Amount | 99.816% |  |  |  |  |  |
Interest Rate Swap |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Weighted average interest rate on all outstanding borrowings |  |  | 2.71% |  | 2.71% |  |

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