PROPOSED MERGER WITH WISCONSIN ENERGY CORPORATION (Details) (USD $)	1 Months Ended
Jun. 30, 2014 customer
Business Combinations [Abstract]
Number of Wisconsin Energy shares per Integrys Energy Group share	1.128
Cash per share of Integrys Energy Group common stock	$ 18.58
Integrys Energy Group shareholder's ownership percentage of combined company	28.00%
Wisconsin Energy shareholder's ownership percentage of combined company	72.00%
Number of total natural gas and electric customers upon closing of the merger	4,300,000

The cash to be received per share of Integrys Energy Group common stock owned under the merger agreement.

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- Definition

Integrys Energy Group ownership percentage of combined company upon closing of the merger agreement.

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- Definition

Number of total natural gas and electric customers across Wisconsin, Illinois, Michigan, and Minnesota upon closing of the merger agreement between Integrys Energy Group and Wisconsin Energy Corporation.

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- Definition

Number of Wisconsin Energy Corporation shares to be received for each share of Integrys Energy Group under the merger agreement at the close of the transaction.

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Wisconsin Energy Corporation shareholders ownership percentage of combined company upon closing of the merger agreement.

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No definition available.

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