| Document and Entity Information | Sep. 04, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 04, 2024 |
| Entity File Number | 001-36695 |
| Entity Registrant Name | Pathfinder Bancorp, Inc. MD |
| Entity Central Index Key | 0001609065 |
| Entity Incorporation, State or Country Code | MD |
| Entity Tax Identification Number | 38-3941859 |
| Entity Address, Address Line One | 214 West First Street |
| Entity Address, City or Town | Oswego |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 13126 |
| City Area Code | 315 |
| Local Phone Number | 343-0057 |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | PBHC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
