REGULATORY ENVIRONMENT (Details) - Public Service Commission of Wisconsin (PSCW) - 2016 rates - USD ($) $ in Millions	1 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Regulatory environment
Approved return on equity (as a percent)		10.00%
Approved common equity component (as a percent)		51.00%
Retail electric rates
Regulatory environment
Approved annual increase (decrease) in rates		$ (7.9)
Approved rate increase (decrease), as a percent		(0.80%)
Authorized revenue requirement for ReACT	$ 275.0	$ 275.0
Percent fuel costs can vary from the rate case approved costs before deferral is required		2.00%
Retail natural gas rates
Regulatory environment
Approved annual increase (decrease) in rates		$ (6.2)
Approved rate increase (decrease), as a percent		(2.10%)

Percentage of public utility's approved equity to capital, including debt and equity.

No definition available.

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

- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

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

- Definition

Percentage of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

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

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

The authorized revenue requirement for ReACT that was used to calculate the ReACT deferral.

+ References

No definition available.

+ Details

Name:	wps_AuthorizedRevenueRequirementForReACT
Namespace Prefix:	wps_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the threshold percentage that actual fuel and purchased power costs can vary from costs charged to customers before deferral is required.

+ References

No definition available.

+ Details

Name:	wps_PercentDeviationFromRateCaseFuelPurchasedPowerCostsBeforeDeferralRequired
Namespace Prefix:	wps_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RegulatoryAgencyAxis=wps_PublicServiceCommissionOfWisconsinPSCWMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	wps_RateCaseYearAxis=wps_Rates2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=wps_ElectricRateRequestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=wps_NaturalGasRateRequestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: