Document And Entity Information
| Document And Entity Information | Jun. 13, 2019 |
| Document Information [Line Items] | |
| EntityRegistrantName | GENERAC HOLDINGS INC. |
| DocumentType | 8-K |
| DocumentPeriodEndDate | Jun. 13, 2019 |
| EntityIncorporationStateCountryCode | DE |
| EntityFileNumber | 001-34627 |
| EntityTaxIdentificationNumber | 20-5654756 |
| EntityAddressAddressLine1 | S45 W29290 Hwy 59 |
| EntityAddressCityOrTown | Waukesha |
| EntityAddressStateOrProvince | WI |
| EntityAddressPostalZipCode | 53189 |
| CityAreaCode | 262 |
| LocalPhoneNumber | 544-4811 |
| Security12bTitle | Common Stock |
| TradingSymbol | GNRC |
| SecurityExchangeName | NYSE |
| WrittenCommunications | false |
| SolicitingMaterial | false |
| PreCommencementTenderOffer | false |
| PreCommencementIssuerTenderOffer | false |
| AmendmentFlag | false |
| EntityCentralIndexKey | 0001474735 |
| EntityEmergingGrowthCompany | false |