GUARANTEES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Guarantees
Total guarantees	$ 568.6
Guarantees expiring in less than 1 year	379.6
Guarantees expiring within 1 to 3 years	2.0
Guarantees with expiration over 3 years	187.0
Guarantees supporting commodity transactions of subsidiaries
Guarantees
Total guarantees	189.3
Guarantees expiring in less than 1 year	105.1
Guarantees expiring within 1 to 3 years	0
Guarantees with expiration over 3 years	84.2
Guarantees supporting commodity transactions of subsidiaries \| IBS
Guarantees
Total guarantees	5.0
Guarantees supporting commodity transactions of subsidiaries \| ITF
Guarantees
Total guarantees	0.4
Guarantees supporting commodity transactions of subsidiaries \| MERC
Guarantees
Total guarantees	127.4
Guarantees supporting commodity transactions of subsidiaries \| MGU
Guarantees
Total guarantees	44.7
Guarantees supporting commodity transactions of subsidiaries \| PDI
Guarantees
Total guarantees	11.8
Standby letters of credit
Guarantees
Total guarantees	1.2
Guarantees expiring in less than 1 year	1.1
Guarantees expiring within 1 to 3 years	0.1
Guarantees with expiration over 3 years	0
Standby letters of credit \| ITF, MERC, MGU, NSG, PDI, PGL, and WPS
Guarantees
Total guarantees	1.2
Surety bonds
Guarantees
Total guarantees	25.1
Guarantees expiring in less than 1 year	25.0
Guarantees expiring within 1 to 3 years	0.1
Guarantees with expiration over 3 years	0
Other guarantees
Guarantees
Total guarantees	73.5
Guarantees expiring in less than 1 year	0
Guarantees expiring within 1 to 3 years	0
Guarantees with expiration over 3 years	73.5
Other guarantees \| Texas Retail Electric Marketing Business
Guarantees
Total guarantees	10.0
Other guarantees \| ITF
Guarantees
Total guarantees	11.2
Other guarantees \| PDI
Guarantees
Total guarantees	46.1
Other indemnifications
Guarantees
Total guarantees	6.2
Guarantees temporarily retained related to the sale of IES's retail energy business
Guarantees
Total guarantees	279.5
Guarantees expiring in less than 1 year	248.4
Guarantees expiring within 1 to 3 years	1.8
Guarantees with expiration over 3 years	29.3
Period of time after the sale of IES for which guarantees will be provided	6 months
Guarantees supporting commodity transactions temporarily retained by Integrys Energy Group \| IES's retail energy business
Guarantees
Total guarantees	267.4
Standby letters of credit temporarily retained by Integrys Energy Group \| IES's retail energy business
Guarantees
Total guarantees	6.9
Surety bonds temporarily retained by Integrys Energy Group \| IES's retail energy business
Guarantees
Total guarantees	3.4
Other guarantees temporarily retained by Integrys Energy Group \| WPS Beaver Falls Generation, LLC and WPS Syracuse Generation, LLC
Guarantees
Total guarantees	1.8
Guarantee obligation maximum exposure related to open transactions \| IES's retail energy business
Guarantees
Total guarantees	$ 168.9

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No definition available.

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- Definition

Represents the maximum potential payments with respect to the entity's guarantees that expire after three years.

+ References

No definition available.

+ Details

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Represents the maximum potential payments with respect to the entity's guarantees that expire within one to three years.

+ References

No definition available.

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Term of the guarantee or each group of similar guarantees.

+ References

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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