| Document and Entity Information | Jul. 21, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jul. 21, 2021 |
| Entity File Number | 001-13349 |
| Entity Registrant Name | BAR HARBOR BANKSHARES |
| Entity Incorporation, State or Country Code | ME |
| Entity Tax Identification Number | 01-0393663 |
| Entity Address, Address Line One | PO Box 400 |
| Entity Address, Adress Line Two | 82 Main Street |
| Entity Address, State or Province | ME |
| Entity Address, City or Town | Bar Harbor |
| Entity Address, Postal Zip Code | 04609-0400 |
| City Area Code | 207 |
| Local Phone Number | 288-3314 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $2.00 per share |
| Trading Symbol | BHB |
| Security Exchange Name | NYSEAMER |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000743367 |
| Amendment Flag | false |
