| Document and Entity Information | Nov. 20, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 20, 2020 |
| Entity Registrant Name | CSB BANCORP INC /OH |
| Entity Central Index Key | 0000880417 |
| Entity Emerging Growth Company | false |
| Entity File Number | 0-21714 |
| Entity Incorporation, State or Country Code | OH |
| Entity Tax Identification Number | 34-1687530 |
| Entity Address, Address Line One | 91 North Clay Street |
| Entity Address, Address Line Two | P.O. Box 232 |
| Entity Address, City or Town | Millersburg |
| Entity Address, State or Province | OH |
| Entity Address, Postal Zip Code | 44654 |
| City Area Code | 330 |
| Local Phone Number | 674-9015 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $6.25 per share |
| Trading Symbol | CSBB |
| Security Exchange Name | NONE |
