GUARANTEES (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015
Guarantees
Total guarantees	$ 306.9
Guarantees expiring in less than 1 year	156.0
Guarantees expiring within 1 to 3 years	0.9
Guarantees with expiration over 3 years	150.0
Guarantees supporting commodity transactions of subsidiaries
Guarantees
Total guarantees	162.5
Guarantees expiring in less than 1 year	91.2
Guarantees expiring within 1 to 3 years	0
Guarantees with expiration over 3 years	71.3
Guarantees supporting commodity transactions of subsidiaries \| IBS
Guarantees
Total guarantees	5.0
Guarantees supporting commodity transactions of subsidiaries \| PDI
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	108.9
Guarantees supporting commodity transactions of subsidiaries \| MGU
Guarantees
Total guarantees	43.2
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
Surety bonds
Guarantees
Total guarantees	25.1
Guarantees expiring in less than 1 year	25.1
Guarantees expiring within 1 to 3 years	0
Guarantees with expiration over 3 years	0
Guarantees temporarily retained related to the sale of IES's retail energy business
Guarantees
Total guarantees	55.7
Guarantees expiring in less than 1 year	38.6
Guarantees expiring within 1 to 3 years	0.8
Guarantees with expiration over 3 years	16.3
Guarantees supporting commodity transactions temporarily retained by Integrys Energy Group \| IES's retail energy business
Guarantees
Total guarantees	52.1
Standby letters of credit temporarily retained by Integrys Energy Group \| IES's retail energy business
Guarantees
Total guarantees	1.2
Surety bonds temporarily retained by Integrys Energy Group \| IES's retail energy business
Guarantees
Total guarantees	2.1
Guarantees related to the sale of WPS Beaver Falls Generation, LLC temporarily retained by Integrys Energy Group \| WPS Beaver Falls Generation, LLC
Guarantees
Total guarantees	0.3
Maximum exposure for guarantees related to open transactions \| IES's retail energy business
Guarantees
Total guarantees	31.5
Other guarantees
Guarantees
Total guarantees	62.4
Guarantees expiring in less than 1 year	0
Guarantees expiring within 1 to 3 years	0
Guarantees with expiration over 3 years	62.4
Other guarantees \| IES's Texas retail marketing business
Guarantees
Total guarantees	10.0
Other guarantees \| PDI
Guarantees
Total guarantees	34.2
Other guarantees \| ITF
Guarantees
Total guarantees	11.2
Other indemnifications primarily for workers compensation coverage
Guarantees
Total guarantees	$ 7.0

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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.

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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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- Definition

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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