Number of shares that have been repurchased during the period and are being held in treasury

No definition available.

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Namespace Prefix:	gnrc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow to reacquire common stock during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

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

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramPeriodInForce1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_TreasuryStockMember
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Period Type:

Note 13 - Stock Repurchase Program (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	56 Months Ended
	Sep. 30, 2018	Mar. 31, 2020	Mar. 31, 2020	Oct. 31, 2016	Aug. 31, 2015
Stock Repurchase Program, Authorized Amount	$ 250,000			$ 250,000	$ 200,000
Stock Repurchase Program, Period in Force (Month)	24 months
Payments for Repurchase of Common Stock			$ 305,547
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)			$ 35.21
Treasury Stock [Member]
Shares Acquired Under Stock Repurchases Program, Shares (in shares)		0	8,676,706