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

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

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- Details

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

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- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

+ Details

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- Definition

Represents the annual cap on authorized rates under a decoupling mechanism, which will be based on total rate case-approved margins rather than being calculated on a per-customer basis.

+ References

No definition available.

+ Details

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- Definition

Represents the income tax amount previously expensed by the entity that was authorized to be recovered.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Represents the amount of deferred regulatory liability related to employee benefits.

+ References

No definition available.

+ Details

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- Definition

Represents the fuel refund including the carrying cost.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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REGULATORY ENVIRONMENT (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 31, 2014
Public Utilities, General Disclosures
Percentage price variance from rate case-approved fuel and purchased power costs before deferral is required	2.00%
Public Service Commission of Wisconsin (PSCW) \| 2015 Rates
Public Utilities, General Disclosures
Approved return on common equity percent reflected in rates of customers	10.20%
Approved percent of capital structure composed of common equity	50.28%
Public Service Commission of Wisconsin (PSCW) \| 2014 Rates
Public Utilities, General Disclosures
Approved return on common equity percent reflected in rates of customers		10.20%
Approved percent of capital structure composed of common equity		50.14%
Public Service Commission of Wisconsin (PSCW) \| 2013 Rates
Public Utilities, General Disclosures
Approved return on common equity percent reflected in rates of customers			10.30%
Approved percent of capital structure composed of common equity			51.61%
Recovery of income tax amounts previously expensed related to the Federal Health Care Reform Act			$ 5.9
Retail natural gas rates \| Public Service Commission of Wisconsin (PSCW) \| 2015 Rates
Public Utilities, General Disclosures
Approved annual increase (decrease) in rates for customers	(15.4)
Retail natural gas rates \| Public Service Commission of Wisconsin (PSCW) \| 2014 Rates
Public Utilities, General Disclosures
Approved annual increase (decrease) in rates for customers		4.0
Retail natural gas rates \| Public Service Commission of Wisconsin (PSCW) \| 2013 Rates
Public Utilities, General Disclosures
Approved annual increase (decrease) in rates for customers			(3.4)
Deferral related to pension and other employee benefit costs			2.1
Annual cap for decoupling			8.0
Retail electric rates \| Public Service Commission of Wisconsin (PSCW) \| 2015 Rates
Public Utilities, General Disclosures
Approved annual increase (decrease) in rates for customers	24.6
Percentage price variance from rate case-approved fuel and purchased power costs before deferral is required	2.00%
Retail electric rates \| Public Service Commission of Wisconsin (PSCW) \| 2014 Rates
Public Utilities, General Disclosures
Approved annual increase (decrease) in rates for customers		(12.8)
Retail electric rates \| Public Service Commission of Wisconsin (PSCW) \| 2013 Rates
Public Utilities, General Disclosures
Approved annual increase (decrease) in rates for customers			28.5
Fuel refund			20.5
Deferral related to pension and other employee benefit costs			7.3
Annual cap for decoupling			14.0
Retail electric rates \| Michigan Public Service Commission (MPSC) \| 2015 Rates
Public Utilities, General Disclosures
Requested annual increase (decrease) in rates for customers				$ 5.7
Requested return on common equity percent				10.60%
Requested percent of capital structure composed of common equity				50.48%