v3.3.1.900
Document And Entity Information - USD ($)
12 Months Ended
Dec. 31, 2015
Feb. 19, 2016
Jun. 30, 2015
Entity Registrant Name GENERAC HOLDINGS INC.    
Entity Central Index Key 0001474735    
Trading Symbol gnrc    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer Yes    
Entity Common Stock, Shares Outstanding (in shares)   66,366,949  
Entity Public Float     $ 2,707,473,704
Document Type 10-K    
Document Period End Date Dec. 31, 2015    
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus FY    
Amendment Flag false