The gains (losses) included in results of operations resulting from the ordinary retirement of utility property, plant and equipment, which do not qualify for treatment as discontinued operations. This item does not include any gain (loss) recognized on land.

No definition available.

+ Details

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

- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

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

- Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Composite depreciation rate for public utility plants in service.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

Name:	dei_LegalEntityAxis=teg_MGUMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	dei_LegalEntityAxis=teg_NSGMember
Namespace Prefix:
Data Type:	na
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- Details

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

- Details

Name:	dei_LegalEntityAxis=teg_WPSMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_SoftwareAndSoftwareDevelopmentCostsMember
Namespace Prefix:
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES PROPERTY, PLANT, AND EQUIPMENT (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, plant, and equipment
Gain (loss) on retirement of utility property, excluding land	0
Software \| Minimum
Property, plant, and equipment
Useful life	3 years
Software \| Maximum
Property, plant, and equipment
Useful life	15 years
MERC
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	2.49%	1.88%	3.07%
MERC \| Minnesota Public Utilities Commission (MPUC)
Property, plant, and equipment
Reduction to depreciation expense		2.0
MGU
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	2.65%	1.93%	2.71%
NSG
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	2.44%	2.44%	2.43%
PGL
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	3.20%	3.19%	3.16%
WPS \| Electric
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	2.73%	2.79%	2.87%
WPS \| Natural gas
Property, plant, and equipment
Annual utility composite depreciation rate (as a percent)	2.17%	2.19%	2.21%