Business Description - Summary of Outstanding Equity and Economic Ownership Interest (Detail) - shares shares in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Description [Line Items]
OP Units	4,455	6,948
Broadstone Net Lease, LLC
Business Description [Line Items]
Percent Ownership of OP, Shares of Common Stock	92.70%	93.70%	92.70%
Percent Ownership of OP, OP Units	7.30%	6.30%	7.30%
Percent Ownership of OP, Total Diluted Shares	100.00%	100.00%	100.00%
Ownership Interest
Business Description [Line Items]
Shares of Common Stock	145,609	104,006	88,055
OP Units	11,399	6,948	6,948
Total Diluted Shares	157,008	110,954	95,003