COMMON EQUITY (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Dividend Payment Restrictions
Total restricted net assets	$ 1,326.8
Equity in undistributed earnings of 50% or less owned investees accounted under equity method investments	29.5
Capital Transactions with Parent
Common stock dividends paid	28.0	27.1
Maximum
Dividend Payment Restrictions
Debt to capitalization ratio required to be maintained (as a percent)	65.00%
Equity method investment, ownership interest (as a percent)	50.00%
Maximum \| Public Service Commission of Wisconsin (PSCW)
Dividend Payment Restrictions
Percentage of previous period's dividend as restriction on current period dividends	103.00%
Minimum
Dividend Payment Restrictions
Percentage of common stockholder's equity to total capitalization required to be maintained	25.00%
Minimum \| Public Service Commission of Wisconsin (PSCW)
Dividend Payment Restrictions
Common equity ratio required to be maintained (as a percent)	51.00%
Integrys Energy Group
Capital Transactions with Parent
Common stock dividends paid	$ 28.0

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(e)(3)(ii))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph e

-Subparagraph 3

-Article 4

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

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- Definition

The distributions of earnings to an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

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Amount of consolidated retained earnings that represent undistributed (not yet received) earnings from 50% or less owned persons accounted for by the equity method (equity method investees).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6462270&loc=d3e57205-112772

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- Definition

Represents the common equity ratio which is required to be maintained.

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Represents the percentage of common stockholders equity to total capitalization for dividend payment restrictions.

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Represents the maximum debt to capitalization ratio.

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Represents the percentage of previous period's dividend as restriction on current period's dividends.

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