Note 15 - Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Amount Financed by Dealers	$ 40.6	$ 36.5

Amount financed by dealers to purchase goods from the entity.

No definition available.

Name:	gnrc_AmountFinancedByDealers
Namespace Prefix:	gnrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant