| Document And Entity Information | Jun. 15, 2019 |
| Document Information [Line Items] | |
| EntityRegistrantName | Cable One, Inc. |
| DocumentType | 8-K |
| DocumentPeriodEndDate | Jun. 15, 2019 |
| EntityIncorporationStateCountryCode | DE |
| EntityFileNumber | 001-36863 |
| EntityTaxIdentificationNumber | 13-3060083 |
| EntityAddressAddressLine1 | 210 E. Earll Drive |
| EntityAddressCityOrTown | Phoenix |
| EntityAddressStateOrProvince | AZ |
| EntityAddressPostalZipCode | 85012 |
| CityAreaCode | 602 |
| LocalPhoneNumber | 364-6000 |
| WrittenCommunications | false |
| SolicitingMaterial | false |
| PreCommencementTenderOffer | false |
| PreCommencementIssuerTenderOffer | false |
| Security12bTitle | Common Stock |
| TradingSymbol | CABO |
| SecurityExchangeName | NYSE |
| AmendmentFlag | false |
| EntityCentralIndexKey | 0001632127 |
| EntityEmergingGrowthCompany | false |
