Name:	gnrc_AmortizationOfDeferredRevenueOnExtendedWarrantyContracts
Namespace Prefix:	gnrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount as of the balance sheet date of the aggregate extended product warranty liability. Does not include the ending balance for the standard product warranty liability.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-8

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (c)(5)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-8

Name:	us-gaap_ExtendedProductWarrantyAccrual
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of increase in the extended product warranty accrual from warranties issued. Excludes standard product warranties.

Name:	us-gaap_ExtendedProductWarrantyAccrualWarrantiesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount as of the balance sheet date of the aggregate standard product warranty liability. Does not include the balance for the extended product warranty liability.

Name:	us-gaap_StandardProductWarrantyAccrual
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of decrease in the standard product warranty accrual from payments made in cash or in kind to satisfy claims under the terms of the standard product warranty. Excludes extended product warranties.

Name:	us-gaap_StandardProductWarrantyAccrualPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of increase (decrease) in the standard product warranty accrual from changes in estimates attributable to preexisting product warranties. Excludes extended product warranties.

Name:	us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of increase in the standard product warranty accrual from warranties issued. Excludes extended product warranties.