Note 14 - Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income attributable to Generac Holdings Inc.		$ 75,574	$ 75,776	$ 182,393	$ 162,682
Redeemable noncontrolling interest redemption value adjustment		(1,485)	(6,912)	191	(16,882)
Net income attributable to common shareholders		$ 74,089	$ 68,864	$ 182,584	$ 145,800
Weighted average shares, basic (in shares)		61,973,447	61,579,564	61,878,500	61,659,817
Dilutive effect of stock compensation awards (in shares)	[1]	797,145	640,734	640,705	606,323
Diluted shares (in shares)		62,770,592	62,220,298	62,519,205	62,266,140
Basic (in dollars per share)		$ 1.20	$ 1.12	$ 2.95	$ 2.36
Diluted (in dollars per share)		$ 1.18	$ 1.11	$ 2.92	$ 2.34

[1] Excludes approximately 38,900 and 48,200 stock options for the three and nine months ended September 30, 2018, respectively, as the impact of such awards was anti-dilutive. There were no awards with an anti-dilutive impact for the three and nine months ended September 30, 2019.