Represents the fair value of derivative contracts excluding impact of credit risk.

No definition available.

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Namespace Prefix:	gnrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of new contracts entered into during the period mentioned.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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Period Type:	duration

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

High end period remaining until maturity for the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_CostOfSalesMember
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Data Type:	na
Balance Type:
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- Details

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- Details

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- Details

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- Details

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Note 3 - Derivative Instruments and Hedging Activities (Details Textual) $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 23, 2013	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Commodity Contract [Member] \| Maximum [Member]
Derivative, Higher Remaining Maturity Range				1 year 180 days
Commodity Contract [Member] \| Cost of Sales [Member] \| Not Designated as Hedging Instrument [Member]
Derivative, Gain (Loss) on Derivative, Net		$ (667)	$ (106)	$ (1,708)	$ (154)
Commodity Contract [Member]
Derivative, Number of Instruments Held		3	2	3	2	3
Foreign Exchange Contract [Member] \| Maximum [Member]
Derivative, Higher Remaining Maturity Range				1 year
Foreign Exchange Contract [Member] \| Cost of Sales [Member] \| Not Designated as Hedging Instrument [Member]
Derivative, Gain (Loss) on Derivative, Net		$ (107)	$ (93)	$ (465)	$ (190)
Foreign Exchange Contract [Member]
Derivative, Number of Instruments Held		3	1	3	1	1
Interest Rate Swap [Member]
Number of New Contracts Entered	2
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ (1,065)	$ 989	$ (2,071)	$ (719)
Commodity and Foreign Currency Contracts [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		(774)	$ (199)	(2,173)	$ (344)
Derivative Assets (Liabilities), Net Fair Value of Derivative Contracts, Excluding Impact of Credit Risk		$ (5,636)		$ (5,636)		$ (1,727)