| Document And Entity Information | Jul. 30, 2019 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Jul. 30, 2019 |
| Entity Registrant Name | STAG INDUSTRIAL, INC. |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 1-34907 |
| Entity Tax Identification Number | 27-3099608 |
| Entity Address, Address Line One | One Federal Street, 23rd Floor |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02110 |
| City Area Code | 617 |
| Local Phone Number | 574-4777 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001479094 |
| Amendment Flag | false |
| Common stock, $0.01 par value per share | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Common stock, $0.01 par value per share |
| Trading Symbol | STAG |
| Security Exchange Name | NYSE |
| 6.875% Series C Cumulative Redeemable Preferred Stock ($0.01 par value) | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | 6.875% Series C Cumulative Redeemable Preferred Stock ($0.01 par value) |
| Trading Symbol | STAG-PC |
| Security Exchange Name | NYSE |
