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Data Type:	xbrli:monetaryItemType
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Represents the amount of unrealized (holding) gains or losses for the period which are included in the statement of income. Such unrealized (holding) gains or losses relate to those assets and liabilities for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

No definition available.

Name:	teg_FairValueAssetsLiabilitiesMeasuredOnRecurringBasisUnrealizedGainLossIncludedInEarnings
Namespace Prefix:	teg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the total unrealized gains or losses for the period, arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are recorded as regulatory assets or liabilities.

No definition available.

Name:	teg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilityUnrealizedLossesRecordedAsRegulatoryAssetsOrLiabilities
Namespace Prefix:	teg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of unrealized gain (loss) recognized in earnings related to discontinued operations, arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (level 3).

No definition available.

Name:	teg_Netunrealizedgainlossrelatedtodiscontinuedoperations
Namespace Prefix:	teg_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Details

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

Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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

Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Transfers out of assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of gain (loss) recognized in other comprehensive income, arising from assets, liabilities and financial instruments classified in shareholders' equity measured at fair value on a recurring basis using unobservable inputs (level 3).