v3.19.3.a.u2
Summary of Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2019
USD ($)
Lease
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Sep. 30, 2019
Mar. 31, 2019
Jan. 01, 2019
USD ($)
Sep. 30, 2018
Sep. 30, 2017
Significant Accounting Policies [Line Items]                
Impairment of real estate assets $ 3,452,000 $ 2,061,000 $ 2,608,000          
Weighted average price per square foot $ 226,000              
Sale of real estate description Company recognized real estate sales when all of the following criteria were met: (i) a sale was consummated, (ii) the buyer had demonstrated an adequate commitment to pay for the property, (iii) the Company’s receivable was not subject to future subordination, and (iv) the Company had transferred the risks and rewards of ownership to the buyer and did not have continuing involvement.              
Lessor operating lease description A lease arrangement was classified as an operating lease if none of the following criteria were met: (i) ownership transferred to the lessee prior to or shortly after the end of the lease term, (ii) the lessee had a bargain purchase option during or at the end of the lease term, (iii) the lease term was greater than or equal to 75% of the underlying property’s estimated useful life, or (iv) the present value of the future minimum lease payments (excluding executory costs) was greater than or equal to 90% of the fair value of the leased property. If one or more of these criteria were met, and the minimum lease payments were determined to be reasonably predictable and collectible, the lease arrangement was generally accounted for as a direct financing lease. Consistent with ASC 840, Leases, if the fair value of the land component was 25% or more of the total fair value of the leased property, the land was considered separately from the building for purposes of applying the lease term and minimum lease payments criterion in (iii) and (iv) above              
Lease term as percentage of property's useful life 75.00%              
Present value of future minimum lease payments as percentage of fair value of leased property 90.00%              
Fair value of land component as percentage of leased property 25.00%              
Obligation to fund capital improvements $ 0              
Percentage of income tax benefit likely of being realized upon settlement more than 50%              
Uncertain tax positions $ 0 0 0          
Lease liabilities 1,209,000              
Accounted for using the direct financing method 41,890,000 42,000,000            
Income taxes 2,415,000 857,000 624,000          
Other Nonoperating Income (Expenses)                
Significant Accounting Policies [Line Items]                
Income taxes   857,000 $ 624,000          
Prepaid Expenses And Other Assets                
Significant Accounting Policies [Line Items]                
Right-of-use assets 1,614,000              
Restricted cash   377,000            
Tenant and capital reserves   1,136,000            
Accounts Payable And Other Liabilities                
Significant Accounting Policies [Line Items]                
Lease liabilities 1,209,000              
Tenant improvement allowances 2,706,000 $ 2,125,000            
ASU 2018-11                
Significant Accounting Policies [Line Items]                
Right-of-use assets           $ 1,687,000    
Lease liabilities           1,261,000    
Rent liability           7,000    
Ground lease           $ 432,000    
ASU 2016-13                
Significant Accounting Policies [Line Items]                
Accounted for using the direct financing method $ 41,890,000              
Percentage of total assets for investment in direct financing leases 1.10%              
Number of individual leases | Lease 16              
Broadstone Net Lease, LLC                
Significant Accounting Policies [Line Items]                
Percentage of shares owned by, non-controlling interest 6.30% 7.30% 7.60%          
IPO                
Significant Accounting Policies [Line Items]                
Deferred offering costs $ 668,000              
Capitalization Rate                
Significant Accounting Policies [Line Items]                
Impaired assets at fair value assumptions used to estimate fair value       14.58% 14.58%      
Minimum                
Significant Accounting Policies [Line Items]                
Lease term 9 years              
Minimum | Capitalization Rate                
Significant Accounting Policies [Line Items]                
Impaired assets at fair value assumptions used to estimate fair value             7.50% 7.25%
Maximum                
Significant Accounting Policies [Line Items]                
Lease term 29 years              
Maximum | Capitalization Rate                
Significant Accounting Policies [Line Items]                
Impaired assets at fair value assumptions used to estimate fair value             10.00% 12.00%
Weighted Average | Discount Rate                
Significant Accounting Policies [Line Items]                
Impaired assets at fair value assumptions used to estimate fair value       8.00% 8.00%   8.00% 8.00%