Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Excess Purchase Price over Predecessor Basis [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2016	70,261,481		(7,564,874)
Balance at Dec. 31, 2016	$ 702	$ 449,049	$ (262,402)	$ (202,116)	$ 452,119	$ (40,163)	$ 397,189	$ (10)	$ 397,179
Change in noncontrolling interest share	0		0	0	0	0		184
Change in noncontrolling interest share		(2,124)					(2,124)		(1,940)
Net unrealized gain (loss) on derivatives	0	0	0	0	0	3,712	3,712	0	3,712
Foreign currency translation adjustment	$ 0	0	$ 0	0	0	15,191	15,191	(14)	15,177
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price (in shares)	558,692		0
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price	$ 6	2,686	$ 0	0	0	0	2,692	0	2,692
Net share settlement of restricted stock awards (in shares)	0		(39,500)
Net share settlement of restricted stock awards	$ 0	0	$ (1,591)	0	0	0	(1,591)	0	(1,591)
Stock repurchases (in shares)	0		(844,500)
Stock repurchases	$ 0	0	$ (30,012)	0	0	0	(30,012)	0	(30,012)
Share-based compensation	0	10,205	0	0	0	0	10,205	0	10,205
Pension liability adjustment	0	0	0	0	0	62	62	0	62
Redemption value adjustment	0	0	0	0	909	0	909	0	909
Net income attributable to Generac Holdings Inc.	$ 0	0	$ 0	0	157,808	0	157,808		157,808
Net income								119
Net income									157,927
Balance (in shares) at Dec. 31, 2017	70,820,173		(8,448,874)
Balance at Dec. 31, 2017	$ 708	459,816	$ (294,005)	(202,116)	610,836	(21,198)	554,041	279	554,320
Net unrealized gain (loss) on derivatives	0	0	0	0	0	2,924	2,924	0	2,924
Foreign currency translation adjustment	$ 0	0	$ 0	0	0	(5,976)	(5,976)	(2)	(5,978)
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price (in shares)	366,245		0
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price	$ 4	1,737	$ 0	0	0	0	1,741	0	1,741
Net share settlement of restricted stock awards (in shares)	0		(38,186)
Net share settlement of restricted stock awards	$ 0	0	$ (1,812)	0	0	0	(1,812)	0	(1,812)
Stock repurchases (in shares)	0		(560,000)
Stock repurchases	$ 0	0	$ (25,656)	0	0	0	(25,656)	0	(25,656)
Share-based compensation	0	14,563	0	0	0	0	14,563	0	14,563
Pension liability adjustment	0	0	0	0	0	437	437	0	437
Redemption value adjustment	0	0	0	0	(17,970)	0	(17,970)	0	(17,970)
Net income attributable to Generac Holdings Inc.	0	0	0	0	238,257	0	238,257		238,257
Net income								749
Net income									239,006
Cash dividends paid to noncontrolling interest of subsidiary	$ 0	0	$ 0	0	0	0	0	(314)	(314)
Balance (in shares) at Dec. 31, 2018	71,186,418		(9,047,060)
Balance at Dec. 31, 2018	$ 712	476,116	$ (321,473)	(202,116)	831,123	(23,813)	760,549	712	761,261
Net unrealized gain (loss) on derivatives	0	0	0	0	0	(13,855)	(13,855)	0	(13,855)
Foreign currency translation adjustment	$ 0	0	$ 0	0	0	2,210	2,210	(30)	2,180
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price (in shares)	481,308		0
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price	$ 5	6,056	$ 0	0	0	0	6,061	0	6,061
Net share settlement of restricted stock awards (in shares)	0		(55,953)
Net share settlement of restricted stock awards	$ 0	0	$ (3,078)	0	0	0	(3,078)	0	(3,078)
Stock repurchases (in shares)			0
Share-based compensation	0	16,694	$ 0	0	0	0	16,694	0	16,694
Pension liability adjustment	0	0	0	0	0	10,541	10,541	0	10,541
Redemption value adjustment	0	0	0	0	1,253	0	1,253	0	1,253
Net income attributable to Generac Holdings Inc.	0	0	0	0	252,007	0	252,007		252,007
Net income								226
Net income									252,233
Cash dividends paid to noncontrolling interest of subsidiary	0	0	0	0	0	0	0	(285)	(285)
Change in noncontrolling interest shares	$ 0	0	$ 0	0	0	0	0	(154)	(154)
Balance (in shares) at Dec. 31, 2019	71,667,726		(9,103,013)
Balance at Dec. 31, 2019	$ 717	$ 498,866	$ (324,551)	$ (202,116)	$ 1,084,383	$ (24,917)	$ 1,032,382	$ 469	$ 1,032,851