| Document and Entity Information | Jun. 17, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 17, 2021 |
| Entity File Number | 0-16084 |
| Entity Registrant Name | Citizens & Northern Corporation |
| Entity Incorporation, State or Country Code | PA |
| Entity Tax Identification Number | 23-2451943 |
| Entity Address, Address Line One | 90-92 Main Street |
| Entity Address, City or Town | Wellsboro |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 16901 |
| City Area Code | 570 |
| Local Phone Number | 724-3411 |
| 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 $1.00 per share |
| Trading Symbol | CZNC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000810958 |
| Amendment Flag | false |
