v3.21.2

Summary of Significant Accounting Policies - Summary of Reconciliation of Change in Earnout Liability (Details) (Parenthetical) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Fair Value Disclosures [Abstract] |  |  |  |  |
Change In Fair Value Of Earnout Liability | $ 1,059 | [1] | $ (6,362) | $ 5,539 | $ (8,506)
[1] | The $1,059 change in fair value during the three months ended September 30, 2021, represented the difference between the actual cash payments subsequent to June 30, 2021, and the earnout liability's fair value at June 30, 2021.

X
- Definition Change in fair value of earnout liability. + References No definition available. + Details
Name: | bnl_ChangeInFairValueOfEarnoutLiability
Namespace Prefix: | bnl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration