Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

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

- Definition

This represents the fair value adjustment to long-term debt assumed in the acquisition of Integrys.

+ References

No definition available.

+ Details

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

- Definition

Long Term Debt Textuals.

+ References

No definition available.

+ Details

Name:	wec_LongTermDebtTextualsAbstract
Namespace Prefix:	wec_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of long-term debt assumed in a business combination that is due within a year or more after the business combination.

+ References

No definition available.

+ Details

Name:	wec_LongtermDebtAssumedinBusinessCombination
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Offer to buy back $55 million 8% Senior Note

+ References

No definition available.

+ Details

Name:	wec_Offertobuyback55million8SeniorNote
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_TEGSeniorNotesdueJune12016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WisGasDebenturedueSeptember302025MemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_FixedFirstAndRefundingMortgageWWSeries2.625PercentBondsDue2033Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WECSeniorNotesdueJune152018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WECSeniorNotesdueJune152020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WECSeniorNotesdueJune152025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WisElecDebenturedueJune12025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WisElecDebenturedueJune12044Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wec_WisElecDebenturesdueApril12014Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long Term Debt (Details) - USD ($) $ in Millions		1 Months Ended
Long Term Debt (Details) - USD ($) $ in Millions	Sep. 01, 2015	Jul. 31, 2015	Jun. 30, 2015	May. 31, 2015	May. 31, 2014	Apr. 30, 2014	Sep. 30, 2015	Aug. 01, 2015	Dec. 31, 2014
Long Term Debt (Textuals)
Long-term Debt, Current Maturities							$ 606.0		$ 424.1
Integrys
Long Term Debt (Textuals)
Long-term Debt Assumed in Business Combination							$ 3,000.0
Fair Value Adjustment to Long-term Debt			$ 46.2
Integrys \| TEG Senior Notes due June 1, 2016 [Member]
Long Term Debt (Textuals)
Offer to buy back $55 million 8% Senior Note		$ 55.0
Interest rate on long-term debt							8.00%
Long-term Debt, Current Maturities							$ 50.0
Retirement of long-term debt		$ 5.0
Wisconsin Gas \| Wis Gas Debenture due September 30, 2025 [Member] [Member]
Long Term Debt (Textuals)
Proceeds from Issuance of Debt	$ 200.0
Interest rate on long-term debt							3.53%
PGL \| Fixed First and Refunding Mortgage WW Series 2.625 Percent Bonds, Due 2033 [Member]
Long Term Debt (Textuals)
Interest rate on long-term debt							2.625%	1.875%
Long-term Debt, Gross								$ 50.0
WEC Energy Group [Domain] \| WEC Senior Notes due June 15, 2018 [Member]
Long Term Debt (Textuals)
Proceeds from Issuance of Debt			300.0
Interest rate on long-term debt							1.65%
WEC Energy Group [Domain] \| WEC Senior Notes due June 15, 2020 [Member]
Long Term Debt (Textuals)
Proceeds from Issuance of Debt			400.0
Interest rate on long-term debt							2.45%
WEC Energy Group [Domain] \| WEC Senior Notes due June 15, 2025 [Member]
Long Term Debt (Textuals)
Proceeds from Issuance of Debt			$ 500.0
Interest rate on long-term debt							3.55%
Wisconsin Electric \| Wis Elec Debenture due June 1, 2025 [Member]
Long Term Debt (Textuals)
Proceeds from Issuance of Debt				$ 250.0
Interest rate on long-term debt				3.10%
Wisconsin Electric \| Wis Elec Debenture due June 1, 2044 [Member]
Long Term Debt (Textuals)
Proceeds from Issuance of Debt					$ 250.0
Interest rate on long-term debt					4.25%
Wisconsin Electric \| Wis Elec Debentures due April 1, 2014 [Member]
Long Term Debt (Textuals)
Retirement of long-term debt						$ 300.0