The amount for notes payable (written promise to pay), due to related parties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.17)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

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

- Definition

Amount of increase (decrease) of physical assets used in the normal conduct of business and not intended for resale, from reclassification, impairment, donation, or changes classified as other. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2921-110230

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

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

The amount of construction work in progress billed to W.E. Power, LLC, a subsidiary of WEC Energy Group, Inc., for Port Washington Generating Station Units 1 and 2 and Oak Creek expansion Units 1 and 2.

+ References

No definition available.

+ Details

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Namespace Prefix:	wep_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of lease payments made to W.E. Power, LLC, a subsidiary of WEC Energy Group, Inc., for Port Washington Generating Station Units 1 and 2 and Oak Creek expansion Units 1 and 2.

+ References

No definition available.

+ Details

Name:	wep_LeasePaymentsPaidToRelatedParty
Namespace Prefix:	wep_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of miles of electric utility distribution lines.

+ References

No definition available.

+ Details

Name:	wep_Milesofelectricdistributionlines
Namespace Prefix:	wep_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of customers served by the entity.

+ References

No definition available.

+ Details

Name:	wep_NumberOfCustomers
Namespace Prefix:	wep_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Payments made to transfer liabilities to a related party.

+ References

No definition available.

+ Details

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Namespace Prefix:	wep_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Proceeds from assets transferred to related party.

+ References

No definition available.

+ Details

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Namespace Prefix:	wep_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Charges to related parties for services, construction, and/or operations (excluding transactions that are eliminated in consolidated or combined financial statements) during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	wep_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	dei_LegalEntityAxis=wep_BostcoLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=wep_UtilitySegmentMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=wep_UMERCTransferMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_ElectricDistributionMember
Namespace Prefix:
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Related Parties (Details) $ in Millions		12 Months Ended
Related Parties (Details) $ in Millions	Jan. 01, 2017 USD ($) mile customer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Related parties
Proceeds from assets transferred to WBS		$ 13.1	$ 0.0	$ 0.0
Payments for liabilities transferred to WBS		116.0	0.0	0.0
WBS
Related parties
Charges to related party		213.8	11.1	0.0
Charges from related party		310.6	1.3	0.0
Proceeds from assets transferred to WBS		13.1
Payments for liabilities transferred to WBS		116.0
WEC Energy Group \| Bostco
Related parties
Note payable to WEC Energy Group		18.5	19.6
We Power \| Electric utility segment
Related parties
Lease payments to We Power		412.2	410.5	389.0
Construction work in progress billed to We Power		37.9	58.8	41.0
Wisconsin Public Service Corporation
Related parties
Charges to related party		9.0	13.4	0.0
Charges from related party		4.2	4.9	0.0
Wisconsin Gas
Related parties
Charges to related party		60.6	79.4	81.7
Charges from related party		21.5	23.5	20.6
Purchases from related party		$ 5.3	$ 5.3	$ 6.6
UMERC Transfer \| Subsequent event
Related parties
Miles of electric distribution lines transferred \| mile	2,500
Net book value of property, plant, and equipment transferred	$ 83.0
UMERC Transfer \| Subsequent event \| Electric utility segment
Related parties
Number of customers \| customer	27,500
UMERC Transfer \| Subsequent event \| Electric distribution
Related parties
Number of customers \| customer	50