v3.20.2

Sale of Real Estate - Schedule of Sale of Real Estate (Detail) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 USD ($) Property | Jun. 30, 2019 USD ($) Property | Jun. 30, 2020 USD ($) Property | Jun. 30, 2019 USD ($) Property
Real Estate [Line Items] |  |  |  |
Number of properties disposed | Property | 3 | 5 | 13 | 9
Aggregate sale price | $ 10,538 | $ 23,809 | $ 47,723 | $ 35,100
Aggregate carrying value | (8,994) | (20,233) | (36,758) | (29,445)
Gain on sale of real estate | 1,046 | 2,787 | 8,665 | 4,187
Real Estate |  |  |  |
Real Estate [Line Items] |  |  |  |
Additional sales expenses | (498) | (789) | (2,300) | (1,468)
Gain on sale of real estate | $ 1,046 | $ 2,787 | $ 8,665 | $ 4,187

X
- Definition Carrying value of real estate, sold. + References No definition available. + Details
Name: | ck1424182_CarryingValueOfRealEstateSold
Namespace Prefix: | ck1424182_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of rental property disposed. + References No definition available. + Details
Name: | ck1424182_NumberOfRentalPropertyDisposed
Namespace Prefix: | ck1424182_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2443-110228 + Details
Name: | us-gaap_GainLossOnSaleOfProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Cash received for the sale of real estate that is not part of an investing activity during the current period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_RealEstateLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expenses recognized in the period that are directly related to the selling and distribution of products or services. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 + Details
Name: | us-gaap_SellingExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_ProductOrServiceAxis=us-gaap_RealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |