v3.19.3
Document And Entity Information - shares
9 Months Ended
Sep. 30, 2019
Oct. 31, 2019
Document Information [Line Items]    
Entity Central Index Key 0001474735  
Entity Registrant Name GENERAC HOLDINGS INC.  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q3  
Document Fiscal Year Focus 2019  
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2019  
Document Transition Report false  
Entity File Number 001-34627  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 20-5654756  
Entity Address, Address Line One S45 W29290 Hwy 59  
Entity Address, City or Town Waukesha  
Entity Address, State or Province WI  
Entity Address, Postal Zip Code 53189  
City Area Code 262  
Local Phone Number 544-4811  
Title of 12(b) Security Common Stock, $0.01 par value  
Trading Symbol GNRC  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   62,541,881