v3.21.2

Significant Accounting Policies - Summary of Impairment Charges (Detail) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 USD ($) Property | Sep. 30, 2020 USD ($) Property | Sep. 30, 2021 USD ($) Property | Sep. 30, 2020 USD ($) Property
Impaired Long-Lived Assets Held and Used [Line Items] |  |  |  |
Number of properties | Property | 4 | 3 | 5 | 6
Impairment charge | $ | $ 25,989 | $ 14,732 | $ 28,001 | $ 17,399

X
- Definition The number of individual properties owned. + References No definition available. + Details
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Namespace Prefix: | bnl_
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Balance Type: | na
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
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
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X
- Definition The charge against earnings in the period to reduce the carrying amount of real property to fair value. + References Reference 1: 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=123570139&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230 + Details
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Namespace Prefix: | us-gaap_
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Period Type: | duration