v3.19.3.a.u2

Unsecured Credit Agreements - Summary of Unsecured Credit Agreements (Parenthetical) (Detail) $ in Thousands | 6 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2019 USD ($) | Jun. 30, 2019 | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Jan. 31, 2019 Option | Jun. 23, 2017 Option
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount | $ 1,989,451 |  | $ 1,989,451 | $ 1,450,551 |  |
Maturity extension fee on outstanding principal balance percentage | 0.05% |  | 0.05% |  |  |
2020 Unsecured Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt instrument extension options, description |  |  | two six-month extensions |  |  |
1 Month LIBOR | 2019 Unsecured Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Number of option available to extend maturity period | Option |  |  |  |  | 2 |
Revolving Credit Facility | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Number of option available to extend maturity period | Option |  |  |  |  |  | 1
2024 Unsecured Term Loan | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Basis spread on variable rate |  |  |  | 1.90% |  |
2024 Unsecured Term Loan | Unsecured Revolving Credit and Term Loan Agreement | Minimum |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Basis spread on variable rate | 0.85% | 1.50% |  | 1.90% |  |
2024 Unsecured Term Loan | Unsecured Revolving Credit and Term Loan Agreement | Maximum |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Basis spread on variable rate | 1.65% | 2.45% |  |  |  |
Unsecured Debt |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount | $ 1,877,300 |  | $ 1,877,300 | $ 1,371,100 |  |
Unsecured Debt | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount | 652,300 |  | 652,300 | 596,100 |  |
Unsecured Debt | 2019 Unsecured Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount |  |  |  | $ 300,000 |  |
Unsecured Debt | 2020 Unsecured Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount | $ 300,000 |  | $ 300,000 |  |  |
Basis spread on variable rate |  |  | 1.25% |  |  |
Unsecured Debt | 1 Month LIBOR |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate | 1.76% |  | 1.76% | 2.35% |  |
Unsecured Debt | 1 Month LIBOR | 2019 Unsecured Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Basis spread on variable rate |  |  | 1.40% |  |  |
Unsecured Debt | Swingline Revolving Credit Facility |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount |  |  |  | $ 15,000 |  |
Unsecured Debt | Swingline Revolver | 2012 Unsecured Credit Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount |  |  |  | $ 15,000 |  |
Basis spread on variable rate |  |  |  | 5.45% |  |
Unsecured Debt | Revolving Credit Facility | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount | $ 197,300 |  | $ 197,300 | $ 141,100 |  |
Unsecured Debt | Revolving Credit Facility | 1 Month LIBOR | 2012 Unsecured Credit Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount |  |  |  | $ 126,100 |  |
Basis spread on variable rate |  |  |  | 1.20% |  |
Unsecured Debt | Revolving Credit Facility | 1 Month LIBOR | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Basis spread on variable rate |  |  | 1.20% |  |  |
Unsecured Debt | 2024 Unsecured Term Loan | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Carrying amount | $ 190,000 |  | $ 190,000 | $ 190,000 |  |
Unsecured Debt | 2024 Unsecured Term Loan | 1 Month LIBOR | Unsecured Revolving Credit and Term Loan Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Basis spread on variable rate |  |  | 1.25% |  |  |

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