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Investment in Rental Property and Lease Arrangements - Net Investment in Direct Financing Leases (Detail) - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Leases [Abstract] |  |
Undiscounted estimated lease payments to be received | $ 49,524 | $ 72,753
Estimated unguaranteed residual values | 16,049 | 20,358
Unearned income | (34,424) | (51,221)
Reserve for credit losses | (196) | 0
Net investment in direct financing leases | $ 30,953 | $ 41,890

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- Definition Direct financing lease reserve for credit losses. + References No definition available. + Details
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Namespace Prefix: | ck1424182_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Amount of deferred selling profit from direct financing lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981 + Details
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Balance Type: | credit
Period Type: | instant

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- Definition Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981 + Details
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Balance Type: | debit
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X
- Definition Amount of net investment in direct financing lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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X
- Definition Present value expected to be derived from underlying asset, following end of lease term, not guaranteed by lessee or other third party unrelated to lessor. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
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