v3.20.2

Interest Rate Swaps - Summary of Interest-rate Swap Agreements (Detail) - Interest Rate Swap - USD ($) | 6 Months Ended |
--- | --- | ---
Jun. 30, 2020 | Dec. 31, 2019
Derivative [Line Items] |  |
Fair Value | $ (85,678,000) | $ (21,560,000)
Bank of America |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Nov. 30, 2023 |
Derivative, Fixed rate | 2.80% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,194,000) | (1,136,000)
Bank of Montreal One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jul. 31, 2024 |
Derivative, Fixed rate | 1.16% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 40,000,000 |
Fair Value | $ (1,635,000) | 740,000
Bank of Montreal Two |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jan. 31, 2025 |
Derivative, Fixed rate | 1.91% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (1,988,000) | (402,000)
Bank of Montreal Three |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jul. 31, 2025 |
Derivative, Fixed rate | 2.32% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,688,000) | (970,000)
Bank of Montreal Four |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jan. 31, 2026 |
Derivative, Fixed rate | 1.92% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,346,000) | (448,000)
Bank of Montreal Five |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jan. 31, 2026 |
Derivative, Fixed rate | 2.05% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 40,000,000 |
Fair Value | $ (4,040,000) | (1,014,000)
Bank of Montreal Six |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2026 |
Derivative, Fixed rate | 2.33% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 10,000,000 |
Fair Value | $ (1,328,000) | (460,000)
Bank of Montreal Seven |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2026 |
Derivative, Fixed rate | 1.99% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,760,000) | (577,000)
Bank of Montreal Eight |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2027 |
Derivative, Fixed rate | 2.37% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (3,760,000) | (1,306,000)
Bank of Montreal Nine |  |
Derivative [Line Items] |  |
Derivative, Maturity date | May 31, 2029 |
Derivative, Fixed rate | 2.09% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (3,633,000) | (799,000)
Capital One, National Association One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2021 |
Derivative, Fixed rate | 1.05% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 15,000,000 |
Fair Value | $ (213,000) | 143,000
Capital One, National Association Two |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2024 |
Derivative, Fixed rate | 1.58% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 15,000,000 |
Fair Value | $ (935,000) | 10,000
Capital One, National Association Three |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jan. 31, 2026 |
Derivative, Fixed rate | 2.08% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 35,000,000 |
Fair Value | $ (3,549,000) | (911,000)
Capital One, National Association Four |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Apr. 30, 2026 |
Derivative, Fixed rate | 2.68% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 15,000,000 |
Fair Value | $ (2,102,000) | (944,000)
Capital One, National Association Five |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jul. 31, 2026 |
Derivative, Fixed rate | 1.32% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 35,000,000 |
Fair Value | $ (2,182,000) | 720,000
Capital One, National Association Six |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2027 |
Derivative, Fixed rate | 2.37% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (3,738,000) | (1,278,000)
M&T Bank |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Aug. 31, 2021 |
Derivative, Fixed rate | 1.02% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 4,841,000 | 4,912,000
Fair Value | $ (46,000) | 41,000
M&T Bank One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Sep. 30, 2022 |
Derivative, Fixed rate | 2.83% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (1,490,000) | (862,000)
M&T Bank Two |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Nov. 30, 2023 |
Derivative, Fixed rate | 2.65% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,125,000) | (1,038,000)
Regions Bank |  |
Derivative [Line Items] |  |
Derivative, Maturity date | May 31, 2020 |
Derivative, Fixed rate | 2.12% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 50,000,000 |
Fair Value |  | (104,000)
Regions Bank One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2023 |
Derivative, Fixed rate | 1.18% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (962,000) | 376,000
Regions Bank Two |  |
Derivative [Line Items] |  |
Derivative, Maturity date | May 31, 2029 |
Derivative, Fixed rate | 2.11% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (3,753,000) | (827,000)
Regions Bank Three |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jun. 30, 2029 |
Derivative, Fixed rate | 2.03% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (3,579,000) | (651,000)
Truist Financial Corporation One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Apr. 30, 2024 |
Derivative, Fixed rate | 1.99% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (1,749,000) | (451,000)
Truist Financial Corporation Two |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Apr. 30, 2025 |
Derivative, Fixed rate | 2.20% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,403,000) | (781,000)
Truist Financial Corporation Three |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jul. 31, 2025 |
Derivative, Fixed rate | 1.99% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,244,000) | (524,000)
Truist Financial Corporation Four |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Dec. 31, 2025 |
Derivative, Fixed rate | 2.30% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,848,000) | (993,000)
Truist Financial Corporation Five |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jan. 31, 2026 |
Derivative, Fixed rate | 1.93% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,339,000) | (458,000)
U.S. Bank National Association |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jun. 30, 2029 |
Derivative, Fixed rate | 2.03% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (3,553,000) | (681,000)
U S Bank National Association One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Aug. 31, 2029 |
Derivative, Fixed rate | 1.35% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (2,021,000) | 881,000
Wells Fargo Bank One |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Feb. 28, 2021 |
Derivative, Fixed rate | 2.39% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 35,000,000 |
Fair Value | $ (466,000) | (302,000)
Wells Fargo Bank Two |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Oct. 31, 2024 |
Derivative, Fixed rate | 2.72% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 15,000,000 |
Fair Value | $ (1,642,000) | (795,000)
Wells Fargo Bank Three |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Apr. 30, 2027 |
Derivative, Fixed rate | 2.72% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 25,000,000 |
Fair Value | $ (4,075,000) | (1,845,000)
Wells Fargo Bank Four |  |
Derivative [Line Items] |  |
Derivative, Maturity date | Jan. 31, 2028 |
Derivative, Fixed rate | 2.37% |
Variable Rate Index | one-month LIBOR |
Notional Amount | $ 75,000,000 |
Fair Value | $ (11,292,000) | $ (3,914,000)

X
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fixed interest rate related to the interest rate derivative. + References No definition available. + Details
Name: | us-gaap_DerivativeFixedInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the derivative contract matures, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DerivativeMaturityDates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Reference to the index or unit of measurement for the underlying which establishes the pricing terms of the derivative instrument. For example, the basis on the underlying for a natural gas futures contract might be the NYMEX price per million British thermal units (MMBtu). + References No definition available. + Details
Name: | us-gaap_DerivativeUnderlyingBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfAmericaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealSixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealSevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealEightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_BankOfMontrealNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_CapitalOneNationalAssociationOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_CapitalOneNationalAssociationTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_CapitalOneNationalAssociationThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_CapitalOneNationalAssociationFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_CapitalOneNationalAssociationFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_CapitalOneNationalAssociationSixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_MAndTBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_MAndTBankOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_MAndTBankTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_RegionsBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_RegionsBankOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_RegionsBankTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_RegionsBankThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_TruistFinancialCorporationOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_TruistFinancialCorporationTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_TruistFinancialCorporationThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_TruistFinancialCorporationFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_TruistFinancialCorporationFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_USBankNationalAssociationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_USBankNationalAssociationOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_WellsFargoBankOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_WellsFargoBankTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_WellsFargoBankThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=ck1424182_WellsFargoBankFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |