Investment in Related Party

No definition available.

Name:	pegi_InvestmentinRelatedParty
Namespace Prefix:	pegi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Ownership Interest in the Company by Pattern Development

+ References

No definition available.

+ Details

Name:	pegi_OwnershipInterestintheCompanybyPatternDevelopment
Namespace Prefix:	pegi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Ownership Percentage

+ References

No definition available.

+ Details

Name:	pegi_OwnershipPercentage
Namespace Prefix:	pegi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Schedule Of Description Of Business [Line Items]

+ References

No definition available.

+ Details

Name:	pegi_ScheduleOfDescriptionOfBusinessLineItems
Namespace Prefix:	pegi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestmentAggregateCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=pegi_PatternDevelopment2.0Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=pegi_PatternDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=pegi_HatchetRidgeWindLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=pegi_StJosephsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=pegi_SpringValleyMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=pegi_SantaIsabelMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=pegi_OcotilloMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	dei_LegalEntityAxis=pegi_PatternGulfWindLLCMember
Namespace Prefix:
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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- Details

Name:	dei_LegalEntityAxis=pegi_GKGreenPowerKanagiMember
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- Details

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Organization - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Jul. 27, 2017
Schedule Of Description Of Business [Line Items]
Purchases from related party	$ 27.0
Pattern Development 2.0 [Member]
Schedule Of Description Of Business [Line Items]
Investment in related party	86.3		$ 60.0
Equity method investment, aggregate cost	$ 153.6
Percentage of ownership	29.00%
Pattern Development [Member]
Schedule Of Description Of Business [Line Items]
Ownership Interest in the Company by Pattern Development		0.40%
Hatchet Ridge [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
St Josephs [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Spring Valley [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Pattern Santa Isabel LLC [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Ocotillo [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Pattern Gulf Wind LLC [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Lost Creek Wind, LLC [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Green Power Tsugaru G.K. [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
Green Power Generation G.K. [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
GK Green Power Otsuki [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
GK Green Power Kanagi [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%
GK Green Power Futtsu [Member]
Schedule Of Description Of Business [Line Items]
Ownership percentage	100.00%