v3.4.0.3

General Information - Reclassifications (Details) $ in Millions	3 Months Ended
	Mar. 31, 2015 USD ($)
Income Statement Reclassification
Item Effected [Line Items]
Prior Period Income Statement Reclassification Treasury Grant	$ 2.5
Cash Flow Statement Reclassification
Item Effected [Line Items]
Prior Period Cash Flow Statement Reclassification Depreciation and Amortization	0.9
Prior Period Cash Flow Statement Reclassification Other Operating Activities	3.7
Prior period cash flow statment reclassification other investing activities	$ 3.7

X

- 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

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

X

- Definition

The amount reclassified from depreciation and amortization to other operating activities on the prior period cash flow statement

+ References

No definition available.

+ Details

Name:	wec_PriorPeriodCashFlowStatementReclassificationDepreciationandAmortization
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The amount reclassified of nonqualified pension and OPEB contributions from other operation activities to contributions to pension and OPEB plans on the prior period cash flow statement

+ References

No definition available.

+ Details

Name:	wec_PriorPeriodCashFlowStatementReclassificationOtherOperatingActivities
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The amount reclassified from treasury grant to depreciation and amortization on the prior period income statement.

+ References

No definition available.

+ Details

Name:	wec_PriorPeriodIncomeStatementReclassificationTreasuryGrant
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The amount reclassified from other investing activities to capital expenditures on the prior period cash flow statement.

+ References

No definition available.

+ Details

Name:	wec_Priorperiodcashflowstatmentreclassificationotherinvestingactivities
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	wec_QuantifyingReclassificationInCurrentPeriodFinancialStatementsByNatureOfReclassificationAxis=wec_IncomeStatementReclassificationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	wec_QuantifyingReclassificationInCurrentPeriodFinancialStatementsByNatureOfReclassificationAxis=wec_CashFlowStatementReclassificationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: