| Document and Entity Information | Aug. 17, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 17, 2021 |
| Entity File Number | 001-38412 |
| Entity Registrant Name | BRIDGEWATER BANCSHARES, INC. |
| Entity Incorporation, State or Country Code | MN |
| Entity Tax Identification Number | 26-0113412 |
| Entity Address, Address Line One | 4450 Excelsior Boulevard, Suite 100 |
| Entity Address, City or Town | St. Louis Park |
| Entity Address, State or Province | MN |
| Entity Address, Postal Zip Code | 55416 |
| City Area Code | 952 |
| Local Phone Number | 893-6868 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 Par Value |
| Trading Symbol | BWB |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001341317 |
| Amendment Flag | false |
| Current Fiscal Year End Date | --12-31 |
