Wisconsin Electric Power Company PFD 3.60% (WELPP) 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - Jun. 30, 2015 - USD ($) $ in Millions	Total
Entity Information [Line Items]
Entity Registrant Name	WISCONSIN ELECTRIC POWER CO
Entity Central Index Key	107,815
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding	33,289,327
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float	$ 26.9

Consolidated Condensed Income S

Consolidated Condensed Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues	$ 883	$ 905.7	$ 1,967.6	$ 2,132.4
Operating Expenses
Fuel and purchased power	273.9	293.7	571.8	613.6
Cost of gas sold	32.2	50.4	167.7	300.1
Other operation and maintenance	343.2	318.8	685.6	656.4
Depreciation and amortization	77.8	73.3	155	146
Property and revenue taxes	29.4	28.4	58.8	56.9
Total Operating Expenses	756.5	764.6	1,638.9	1,773
Treasury Grant	2.2	3.1	4.7	6.6
Operating Income	128.7	144.2	333.4	366
Equity in earnings of transmission affiliate	12.2	15.3	26.4	30.5
Other Income, net	4	5.8	6.5	6.6
Interest Expense, net	29.5	27.7	58.2	58.6
Income Before Income Taxes	115.4	137.6	308.1	344.5
Income Tax Expense	40.5	47.3	111.5	126.9
Net Income	74.9	90.3	196.6	217.6
Preferred Stock Dividend Requirement	0.3	0.3	0.6	0.6
Earnings Available for Common Stockholder	$ 74.6	$ 90	$ 196	$ 217

Consolidated Condensed Balance

Consolidated Condensed Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment
In service	$ 10,684.5	$ 10,544.4
Accumulated depreciation	(3,501.5)	(3,406.1)
Property, Plant and Equipment in Service, Net	7,183	7,138.3
Construction work in progress	192.1	140.9
Leased facilities, net	2,176.9	2,215
Net Property, Plant and Equipment	9,552	9,494.2
Investments
Equity investment in transmission affiliate	382.9	372.9
Other	0.3	0.2
Total Investments	383.2	373.1
Current Assets
Cash and cash equivalents	11.2	24
Accounts receivable, net	255.1	265.3
Accounts receivable from related parties	40.9	8.1
Accrued revenues	166.6	223.1
Materials, supplies and inventories	291.9	320.5
Deferred Tax Assets, Net, Current	49.4	46.7
Prepayments and other	136.7	158.5
Total Current Assets	951.8	1,046.2
Deferred Charges and Other Assets
Regulatory assets	1,676.6	1,626.9
Other	158.2	106.3
Total Deferred Charges and Other Assets	1,834.8	1,733.2
Total Assets	12,721.8	12,646.7
Capitalization
Common equity	3,495.8	3,412.8
Preferred stock	30.4	30.4
Long-term debt	2,414.6	2,165.5
Capital lease obligations	2,702	2,712.5
Total Capitalization	8,642.8	8,321.2
Current Liabilities
Long-term debt and capital lease obligations due currently	364.9	355.6
Short-term debt	60	306.8
Subsidiary note payable to WEC Energy Group	20.1	22.4
Accounts payable	276.9	287.2
Accounts payable to related parties	91.6	87.8
Accrued payroll and benefits	62.2	87.1
Other	161.4	113.7
Total Current Liabilities	1,037.1	1,260.6
Deferred Credits and Other Liabilities
Regulatory liabilities	618.3	615.9
Deferred income taxes - long term	2,002.9	1,963.9
Pension and other benefit obligations	192.9	254.5
Other	227.8	230.6
Total Deferred Credits and Other Liabilities	3,041.9	3,064.9
Total Capitalization and Liabilities	$ 12,721.8	$ 12,646.7

Consolidated Condensed Statemen

Consolidated Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities
Net Income	$ 196.6	$ 217.6
Reconciliation to cash
Depreciation and amortization	159.6	149.1
Deferred income taxes and investment tax credits, net	40	113.8
Contributions to qualified benefit plans	(100)	0
Change In
Accounts receivable and accrued revenues	33.7	102
Inventories	28.5	35.5
Other current assets	13.5	12.1
Accounts payable	(11.2)	(34.6)
Accrued income taxes, net	52.9	(6.1)
Other current liabilities	(33.2)	(29.3)
Other, net	(39.8)	(41.6)
Cash Provided by Operating Activities	340.6	518.5
Investing Activities
Capital Expenditures	(225.4)	(228.3)
Cost of Removal, Net of Salvage	(9.4)	(9.4)
Investment in transmission affiliate	(2.3)	(6.9)
Other, net	0.4	2.3
Cash Used in Investing Activities	(236.7)	(242.3)
Financing Activities
Dividends paid on common stock	(120)	(220)
Dividends paid on preferred stock	(0.6)	(0.6)
Issuance of long-term debt	250	250
Retirement of Long-term Debt	0	(300)
Change in total short-term debt	(249.1)	(14.1)
Other, net	3	2.5
Cash Used in Financing Activities	(116.7)	(282.2)
Change in Cash and Cash Equivalents	(12.8)	(6)
Cash and Cash Equivalents at Beginning of Period	24	25.1
Cash and Cash Equivalents at End of Period	$ 11.2	$ 19.1

General Information

General Information	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General Information [Text Block]	GENERAL INFORMATION Our accompanying unaudited consolidated condensed financial statements should be read in conjunction with Item 8. Financial Statements and Supplementary Data, in our 2014 Annual Report on Form 10-K. In the opinion of management, we have included all adjustments, normal and recurring in nature, necessary for a fair presentation of the results of operations, cash flows and financial position in the accompanying income statements, statements of cash flows and balance sheets. The results of operations for the three and six months ended June 30, 2015 are not necessarily indicative of the results which may be expected for the entire fiscal year 2015 because of seasonal and other factors.

Acquisition (Notes)

Acquisition (Notes)	6 Months Ended
	Jun. 30, 2015
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	ACQUISITION On June 29, 2015 , our parent company, Wisconsin Energy, acquired 100% of the outstanding common shares of Integrys, a provider of regulated natural gas and electricity, as well as nonregulated renewable energy and compressed natural gas products and services. The combined company was renamed WEC Energy Group, Inc. Our parent company now owns approximately 60% of ATC, a for-profit transmission company regulated by the Federal Energy Regulatory Commission (FERC). Our ownership interest in ATC did not change as a result of the acquisition. The acquisition of Integrys provides WEC Energy Group increased access to scale, the potential for long-term cost savings through a combination of lower capital and operating costs, and the potential for operating efficiencies . Pursuant to the Merger Agreement, Integrys’ shareholders received 1.128 shares of Wisconsin Energy common stock and $18.58 in cash per Integrys share of common stock. The total consideration transferred was based on the closing price of Wisconsin Energy common stock on June 29, 2015. The acquisition was subject to the approvals of various government agencies, including the FERC, Federal Communications Commission (FCC), Public Service Commission of Wisconsin (PSCW), Illinois Commerce Commission (ICC), Michigan Public Service Commission (MPSC), and Minnesota Public Utilities Commission (MPUC). Approvals were obtained from all agencies subject to several conditions. The PSCW order included the following conditions: • We will be subject to an earnings sharing mechanism for three years beginning January 1, 2016. Under the earnings sharing mechanism, any additional earnings over the authorized rate of return will be shared with ratepayers. • Any future electric generation projects affecting Wisconsin ratepayers submitted by WEC Energy Group or its subsidiaries will first consider the extent to which existing intercompany resources can meet energy and capacity needs.

Acquisition Acquisition (Notes)

Acquisition Acquisition (Notes)	6 Months Ended
	Jun. 30, 2015
Acquisition [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	ACQUISITION On June 29, 2015 , our parent company, Wisconsin Energy, acquired 100% of the outstanding common shares of Integrys, a provider of regulated natural gas and electricity, as well as nonregulated renewable energy and compressed natural gas products and services. The combined company was renamed WEC Energy Group, Inc. Our parent company now owns approximately 60% of ATC, a for-profit transmission company regulated by the Federal Energy Regulatory Commission (FERC). Our ownership interest in ATC did not change as a result of the acquisition. The acquisition of Integrys provides WEC Energy Group increased access to scale, the potential for long-term cost savings through a combination of lower capital and operating costs, and the potential for operating efficiencies . Pursuant to the Merger Agreement, Integrys’ shareholders received 1.128 shares of Wisconsin Energy common stock and $18.58 in cash per Integrys share of common stock. The total consideration transferred was based on the closing price of Wisconsin Energy common stock on June 29, 2015. The acquisition was subject to the approvals of various government agencies, including the FERC, Federal Communications Commission (FCC), Public Service Commission of Wisconsin (PSCW), Illinois Commerce Commission (ICC), Michigan Public Service Commission (MPSC), and Minnesota Public Utilities Commission (MPUC). Approvals were obtained from all agencies subject to several conditions. The PSCW order included the following conditions: • We will be subject to an earnings sharing mechanism for three years beginning January 1, 2016. Under the earnings sharing mechanism, any additional earnings over the authorized rate of return will be shared with ratepayers. • Any future electric generation projects affecting Wisconsin ratepayers submitted by WEC Energy Group or its subsidiaries will first consider the extent to which existing intercompany resources can meet energy and capacity needs.

Common Equity

Common Equity	6 Months Ended
	Jun. 30, 2015
Stockholders' Equity Note [Abstract]
COMMON EQUITY	COMMON EQUITY Stock Option Activity: The following table identifies non-qualified stock options granted by the Compensation Committee of the Board of Directors of WEC Energy Group (Compensation Committee) to our employees: 2015 2014 Non-qualified stock options granted year to date 495,550 864,860 Estimated fair value per non-qualified stock option $ 5.29 $ 4.18 Assumptions used to value the options using a binomial option pricing model: Risk-free interest rate 0.1% - 2.1% 0.1% - 3.0% Dividend yield 3.7 % 3.8 % Expected volatility 18.0 % 18.0 % Expected forfeiture rate 2.0 % 2.0 % Expected life (years) 5.8 5.8 The risk-free interest rate is based on the U.S. Treasury interest rate whose term is consistent with the expected life of the stock options. Dividend yield, expected volatility, expected forfeiture rate and expected life assumptions are based on WEC Energy Group's historical experience. The following is a summary of WEC Energy Group stock option activity by our employees during the three and six months ended June 30, 2015 : Weighted- Average Weighted- Remaining Aggregate Number of Average Contractual Life Intrinsic Value Stock Options Options Exercise Price (Years) (Millions) Outstanding as of April 1, 2015 6,607,682 $ 32.11 Granted — $ — Exercised (174,369 ) $ 21.07 Outstanding as of June 30, 2015 6,433,313 $ 32.41 Outstanding as of January 1, 2015 6,450,277 $ 30.07 Granted 495,550 $ 52.90 Exercised (512,514 ) $ 22.82 Outstanding as of June 30, 2015 6,433,313 $ 32.41 5.7 $ 80.8 Exercisable as of June 30, 2015 3,800,683 $ 26.10 4.0 $ 71.7 The intrinsic value of WEC Energy Group options exercised by our employees was $4.7 million and $14.6 million for the three and six months ended June 30, 2015 and $2.0 million and $15.9 million for the same periods in 2014 , respectively. Cash received by WEC Energy Group from exercises of its options by our employees was $11.7 million and $16.2 million for the six months ended June 30, 2015 and 2014 , respectively. The actual tax benefit realized for the tax deductions from option exercises for the same periods was $5.9 million and $6.5 million , respectively. The following table summarizes information about WEC Energy Group stock options held by our employees and outstanding as of June 30, 2015 : Options Outstanding Options Exercisable Weighted-Average Weighted-Average Remaining Remaining Number of Exercise Contractual Number of Exercise Contractual Range of Exercise Prices Options Price Life (Years) Options Price Life (Years) $19.74 to $21.11 1,169,925 $ 20.99 3.3 1,169,925 $ 20.99 3.3 $23.88 to $29.35 1,786,018 $ 25.17 3.3 1,786,018 $ 25.17 3.3 $34.88 to $52.90 3,477,370 $ 39.96 7.8 844,740 $ 35.15 6.6 6,433,313 $ 32.41 5.7 3,800,683 $ 26.10 4.0 The following table summarizes information about our employees' non-vested WEC Energy Group stock options during the three and six months ended June 30, 2015 : Weighted-Average Non-Vested Stock Options Number of Options Fair Value Non-vested as of April 1, 2015 2,632,630 $ 4.03 Granted — $ — Vested — $ — Forfeited — $ — Non-vested as of June 30, 2015 2,632,630 $ 4.03 Non-vested as of January 1, 2015 2,767,835 $ 3.65 Granted 495,550 $ 5.29 Vested (630,755 ) $ 3.34 Non-vested as of June 30, 2015 2,632,630 $ 4.03 As of June 30, 2015 , our total compensation costs related to non-vested WEC Energy Group stock options held by our employees and not yet recognized was approximately $3.1 million , which is expected to be recognized over the next 18 months on a weighted-average basis. Restricted Shares: The following restricted stock activity related to our employees occurred during the three and six months ended June 30, 2015 : Weighted-Average Restricted Shares Number of Shares Grant Date Fair Value Outstanding as of April 1, 2015 93,639 Granted — $ — Released — $ — Outstanding as of June 30, 2015 93,639 Outstanding as of January 1, 2015 100,657 Granted 43,212 $ 53.78 Released (50,230 ) $ 37.73 Outstanding as of June 30, 2015 93,639 WEC Energy Group records the market value of the restricted stock awards on the date of grant and then we amortize our share of allocated expense over the vesting period of the awards. The intrinsic value of WEC Energy Group restricted stock vesting and held by our employees was zero and $2.7 million for the three and six months ended June 30, 2015 and zero and $2.3 million for the same periods in 2014 , respectively. The actual tax benefit realized for the tax deductions from released restricted shares was zero and $1.1 million for the three and six months ended June 30, 2015 and zero and $0.9 million for the same periods in 2014 , respectively. As of June 30, 2015 , total compensation cost related to our share of WEC Energy Group restricted stock not yet recognized was approximately $3.3 million , which is expected to be recognized over the next 24 months on a weighted-average basis. Performance Units: In January 2015 and 2014 , the Compensation Committee awarded 187,450 and 224,735 WEC Energy Group performance units, respectively, to our officers and other key employees under the WEC Energy Group Performance Unit Plan. Performance units earned as of December 31, 2014 and 2013 vested and were settled during the first quarter of 2015 and 2014 , and had a total intrinsic value of $11.6 million and $13.1 million , respectively. The actual tax benefit realized for the tax deductions from the settlement of performance units was approximately $4.2 million and $4.7 million , respectively. As of June 30, 2015 , total compensation cost related to our share of WEC Energy Group performance units not yet recognized was approximately $12.3 million , which is expected to be recognized over the next 23 months on a weighted-average basis. Restrictions: Various financing arrangements and regulatory requirements impose certain restrictions on our ability to transfer funds to WEC Energy Group in the form of cash dividends, loans or advances. In addition, under Wisconsin law, we are prohibited from loaning funds, either directly or indirectly, to WEC Energy Group. See Note H -- Common Equity in our 2014 Annual Report on Form 10-K for additional information on these and other restrictions. We do not believe that these restrictions will materially affect our operations or limit any dividend payments in the foreseeable future.

Long Term Debt

Long Term Debt	6 Months Ended
	Jun. 30, 2015
Long-term Debt and Capital Lease Obligations [Abstract]
Long-term Debt [Text Block]	LONG-TERM DEBT In May 2015, we issued $250 million of 3.10% Debentures due June 1, 2025. The net proceeds were used to repay short-term debt and for general corporate purposes. In May 2014, we issued $250 million of 4.25% Debentures due June 1, 2044. The net proceeds were used to repay short-term debt and for general corporate purposes. On April 1, 2014, we used short-term borrowings to retire $300 million of long-term debt that matured.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2015
Fair Value Measurements [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Fair value measurements require enhanced disclosures about assets and liabilities that are measured and reported at fair value and establish a hierarchal disclosure framework which prioritizes and ranks the level of observable inputs used in measuring fair value. Fair value is the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We primarily apply the market approach for recurring fair value measurements and attempt to utilize the best available information. Accordingly, we also utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. We are able to classify fair value balances based on the observability of those inputs. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Assets and liabilities measured and reported at fair value are classified and disclosed in one of the following categories: Level 1 -- Pricing inputs are unadjusted quoted prices available in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Instruments in this category consist of financial instruments such as exchange-traded derivatives, cash equivalents and restricted cash investments. Level 2 -- Pricing inputs are other than quoted prices in active markets, which are either directly or indirectly observable as of the reporting date, and fair value is determined through the use of models or other valuation methodologies. Instruments in this category include non-exchange-traded derivatives such as Over-the-Counter (OTC) forwards and options. Level 3 -- Pricing inputs include significant inputs that are generally less observable from objective sources. The inputs in the determination of fair value require significant management judgment or estimation. At each balance sheet date, we perform an analysis of all instruments subject to fair value reporting and include in Level 3 all instruments whose fair value is based on significant unobservable inputs. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an instrument's level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the instrument. The following tables summarize our financial assets and liabilities by level within the fair value hierarchy: Recurring Fair Value Measures As of June 30, 2015 Level 1 Level 2 Level 3 Total (Millions of Dollars) Assets: Derivatives $ 1.0 $ 1.3 $ 3.6 $ 5.9 Total $ 1.0 $ 1.3 $ 3.6 $ 5.9 Liabilities: Derivatives $ 2.9 $ 4.7 $ — $ 7.6 Total $ 2.9 $ 4.7 $ — $ 7.6 Recurring Fair Value Measures As of December 31, 2014 Level 1 Level 2 Level 3 Total (Millions of Dollars) Assets: Derivatives $ 0.4 $ 5.2 $ 7.0 $ 12.6 Total $ 0.4 $ 5.2 $ 7.0 $ 12.6 Liabilities: Derivatives $ 6.8 $ 0.5 $ — $ 7.3 Total $ 6.8 $ 0.5 $ — $ 7.3 Derivatives reflect positions we hold in exchange-traded derivative contracts and OTC derivative contracts. Exchange-traded derivative contracts, which include futures and exchange-traded options, are generally based on unadjusted quoted prices in active markets and are classified within Level 1. Some OTC derivative contracts are valued using broker or dealer quotations, or market transactions in either the listed or OTC markets utilizing a mid-market pricing convention (the mid-point between bid and ask prices), as appropriate. In such cases, these derivatives are classified within Level 2. Certain OTC derivatives may utilize models to measure fair value. Generally, we use a similar model to value similar instruments. Valuation models utilize various inputs which include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, other observable inputs for the asset or liability, and market-corroborated inputs (i.e., inputs derived principally from or corroborated by observable market data by correlation or other means). Where observable inputs are available for substantially the full term of the asset or liability, the instrument is categorized in Level 2. Certain OTC derivatives are in less active markets with a lower availability of pricing information which might not be observable in or corroborated by the market. When such inputs have a significant impact on the measurement of fair value, the instrument is categorized in Level 3. The following table summarizes the changes to derivatives classified as Level 3 in the fair value hierarchy: Three Months Ended June 30 Six Months Ended June 30 2015 2014 2015 2014 (Millions of Dollars) Beginning Balance $ 3.3 $ 1.7 $ 7.0 $ 3.5 Realized and unrealized gains (losses) — — — — Purchases 3.9 15.6 3.9 15.6 Issuances — — — — Settlements (3.6 ) (3.2 ) (7.3 ) (5.0 ) Transfers in and/or out of Level 3 — — — — Balance as of June 30 $ 3.6 $ 14.1 $ 3.6 $ 14.1 Derivative instruments reflected in Level 3 of the hierarchy include Midcontinent Independent System Operator, Inc. (MISO) Financial Transmission Rights (FTRs) that are measured at fair value each reporting period using monthly or annual auction shadow prices from relevant auctions. Changes in fair value for Level 3 recurring items are recorded on our balance sheet. See Note 6 -- Derivative Instruments for further information on the offset to regulatory assets and liabilities. The carrying amount and estimated fair value of certain of our recorded financial instruments are as follows: June 30, 2015 December 31, 2014 Financial Instruments Carrying Amount Fair Value Carrying Amount Fair Value (Millions of Dollars) Preferred stock, no redemption required $ 30.4 $ 27.0 $ 30.4 $ 27.1 Long-term debt, including current portion $ 2,687.0 $ 2,619.1 $ 2,437.0 $ 2,759.6 The carrying value of net accounts receivable, accounts payable and short-term borrowings approximates fair value due to the short-term nature of these instruments. The fair value of our preferred stock is estimated based upon the quoted market value for the same or similar issues. The fair value of our long-term debt, including the current portion of long-term debt, but excluding capitalized leases and unamortized discount on debt, is estimated based upon quoted market value for the same or similar issues or upon the quoted market prices of U.S. Treasury issues having a similar term to maturity, adjusted for the issuing company's bond rating and the present value of future cash flows.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedges, Assets [Abstract]
DERIVATIVE INSTRUMENTS	DERIVATIVE INSTRUMENTS We utilize derivatives as part of our risk management program to manage the volatility and costs of purchased power, generation and natural gas purchases for the benefit of our customers. Our approach is non-speculative and designed to mitigate risk and protect against price volatility. Regulated hedging programs require prior approval by the PSCW. We record derivative instruments on the balance sheet as an asset or liability measured at its fair value, and changes in the derivative's fair value are recognized currently in earnings unless specific hedge accounting criteria are met or we receive regulatory treatment for the derivative. For most energy related physical and financial contracts in our regulated operations that qualify as derivatives, the PSCW allows the effects of the fair market value accounting to be offset to regulatory assets and liabilities. As of June 30, 2015 , we recognized $7.4 million in regulatory assets and $4.9 million in regulatory liabilities related to derivatives in comparison to $8.4 million in regulatory assets and $12.2 million in regulatory liabilities as of December 31, 2014 . We record our current derivative assets on the balance sheet in prepayments and other current assets and the current portion of the liabilities in other current liabilities. We had no long-term portion of derivative assets as of June 30, 2015 , and the long-term portion of our derivative liabilities of $0.2 million is recorded in other deferred credit and other liabilities as of June 30, 2015 . Our Consolidated Condensed Balance Sheets as of June 30, 2015 and December 31, 2014 include: June 30, 2015 December 31, 2014 Derivative Asset Derivative Liability Derivative Asset Derivative Liability (Millions of Dollars) Natural Gas $ 0.9 $ 2.9 $ 2.3 $ 7.1 Fuel Oil 0.1 — — — FTRs 3.6 — 7.0 — Coal 1.3 4.7 3.3 0.2 Total $ 5.9 $ 7.6 $ 12.6 $ 7.3 Our Consolidated Condensed Income Statements include gains (losses) on derivative instruments used in our risk management strategies under fuel and purchased power for those commodities supporting our electric operations and under cost of gas sold for the natural gas sold to our customers. Our estimated notional volumes and gains (losses) were as follows: Three Months Ended June 30, 2015 Three Months Ended June 30, 2014 Volume Gains (Losses) Volume Gains (Losses) (Millions of Dollars) (Millions of Dollars) Natural Gas 5.9 million Dth $ (3.1 ) 5.4 million Dth $ 1.5 Fuel Oil 0.8 million gallons 0.1 2.4 million gallons 0.4 FTRs 5.9 million MWh 0.8 7.4 million MWh 2.6 Total $ (2.2 ) $ 4.5 Six Months Ended June 30, 2015 Six Months Ended June 30, 2014 Volume Gains (Losses) Volume Gains (Losses) (Millions of Dollars) (Millions of Dollars) Natural Gas 12.3 million Dth $ (6.9 ) 12.6 million Dth $ 5.4 Fuel Oil 1.7 million gallons — 4.4 million gallons 0.6 FTRs 12.1 million MWh 2.9 13.1 million MWh 9.6 Total $ (4.0 ) $ 15.6 As of June 30, 2015 and December 31, 2014 , we posted collateral of $4.4 million and $6.9 million , respectively, in our margin accounts. These amounts are recorded on the balance sheets in other current assets. The fair value amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral are not offset against the fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement. The table below shows derivative assets and derivative liabilities if derivative instruments by counterparty were presented net on the balance sheet as of June 30, 2015 and December 31, 2014 : June 30, 2015 December 31, 2014 Derivative Derivative Derivative Derivative Asset Liability Asset Liability (Millions of Dollars) Gross Amount Recognized on the Balance Sheet $ 5.9 $ 7.6 $ 12.6 $ 7.3 Gross Amount Not Offset on Balance Sheet (a) (0.9 ) (2.9 ) (0.4 ) (6.8 ) Net Amount $ 5.0 $ 4.7 $ 12.2 $ 0.5 (a) Gross Amount Not Offset on Balance Sheet includes cash collateral posted of $2.0 million and $6.4 million as of June 30, 2015 and December 31, 2014 , respectively.

Benefits

Benefits	6 Months Ended
	Jun. 30, 2015
General Discussion of Pension and Other Postretirement Benefits [Abstract]
BENEFITS	BENEFITS The components of our net periodic pension and Other Post-Retirement Employee Benefits (OPEB) costs for the three and six months ended June 30 were as follows: Pension Costs Three Months Ended June 30 Six Months Ended June 30 Benefit Plan Cost Components 2015 2014 2015 2014 (Millions of Dollars) Net Periodic Benefit Cost Service cost $ 3.6 $ 2.2 $ 7.3 $ 4.7 Interest cost 13.1 14.9 26.4 29.7 Expected return on plan assets (20.8 ) (19.8 ) (41.8 ) (39.6 ) Amortization of: Prior service cost 0.5 0.5 1.0 1.0 Actuarial loss 8.9 6.9 17.9 13.5 Net Periodic Benefit Cost $ 5.3 $ 4.7 $ 10.8 $ 9.3 OPEB Costs Three Months Ended June 30 Six Months Ended June 30 Benefit Plan Cost Components 2015 2014 2015 2014 (Millions of Dollars) Net Periodic Benefit Cost Service cost $ 2.1 $ 1.9 $ 4.5 $ 4.0 Interest cost 3.3 3.6 6.7 7.2 Expected return on plan assets (4.0 ) (4.1 ) (8.0 ) (8.1 ) Amortization of: Prior service credit (0.3 ) (0.4 ) (0.6 ) (0.8 ) Actuarial loss 0.3 0.1 0.6 0.1 Net Periodic Benefit Cost $ 1.4 $ 1.1 $ 3.2 $ 2.4 We contributed $100.0 million to our qualified pension plan during the first six months of 2015 . No such contribution was made during the first six months of 2014 . Postemployment Benefits: Postemployment benefits provided to former or inactive employees are recognized when an event occurs. The estimated liability for such benefits was $1.8 million as of both June 30, 2015 and December 31, 2014 .

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2015
Segment Information [Abstract]
Segment Information [Text Block]	SEGMENT INFORMATION Summarized financial information concerning our reportable segments for the three and six months ended June 30, 2015 and 2014 is shown in the following table: Reportable Segments Electric Gas Steam Total (Millions of Dollars) Three Months Ended June 30, 2015 Operating Revenues (a) $ 813.5 $ 61.3 $ 8.2 $ 883.0 Operating Income $ 122.4 $ 6.4 $ (0.1 ) $ 128.7 June 30, 2014 Operating Revenues (a) $ 813.7 $ 83.8 $ 8.2 $ 905.7 Operating Income $ 135.3 $ 8.5 $ 0.4 $ 144.2 Six Months Ended June 30, 2015 Operating Revenues (a) $ 1,682.4 $ 259.2 $ 26.0 $ 1,967.6 Operating Income $ 281.2 $ 45.1 $ 7.1 $ 333.4 June 30, 2014 Operating Revenues (a) $ 1,699.5 $ 406.3 $ 26.6 $ 2,132.4 Operating Income $ 304.2 $ 53.9 $ 7.9 $ 366.0 (a) We account for all intersegment revenues at rates established by the PSCW. Intersegment revenues were not material.

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2015
Variable Interest Entities [Abstract]
Variable Interest Entities Disclosure [Text Block]	VARIABLE INTEREST ENTITIES The primary beneficiary of a variable interest entity must consolidate the related assets and liabilities. Certain disclosures are required by sponsors, significant interest holders in variable interest entities and potential variable interest entities. We assess our relationships with potential variable interest entities such as our coal suppliers, natural gas suppliers, coal and gas transporters, and other counterparties in power purchase agreements and joint ventures. In making this assessment, we consider the potential that our contracts or other arrangements provide subordinated financial support, the potential for us to absorb losses or rights to residual returns of the entity, the ability to directly or indirectly make decisions about the entities' activities and other factors. We have identified a purchased power agreement which represents a variable interest. This agreement is for 236 MW of firm capacity from a gas-fired cogeneration facility and we account for it as a capital lease. The agreement includes no minimum energy requirements over the remaining term of approximately 7 years . We have examined the risks of the entity including operations and maintenance, dispatch, financing, fuel costs and other factors, and have determined that we are not the primary beneficiary of the entity. We do not hold an equity or debt interest in the entity and there is no residual guarantee associated with the purchased power agreement. We have approximately $152.2 million of required payments over the remaining term of this agreement. We believe that the required lease payments under this contract will continue to be recoverable in rates. Total capacity and lease payments under contracts considered variable interests for the six months ended June 30, 2015 and 2014 were $26.8 million and $26.7 million , respectively. Our maximum exposure to loss is limited to the capacity payments under the contract.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	COMMITMENTS AND CONTINGENCIES Environmental Matters: We periodically review our exposure for environmental remediation costs as evidence becomes available indicating that our liability has changed. Given current information, including the following, we believe that future costs in excess of the amounts accrued and/or disclosed on all presently known and quantifiable environmental contingencies will not be material to our financial position or results of operations. We have a program of comprehensive environmental remediation planning for former manufactured gas plant sites and coal combustion product disposal sites. We perform ongoing assessments of our manufactured gas plant sites and related disposal sites, as well as our coal combustion product disposal/landfill sites. We are working with the Wisconsin Department of Natural Resources (WDNR) in our investigation and remediation planning. At this time, we cannot estimate future remediation costs associated with these sites beyond those described below. Manufactured Gas Plant Sites: We have identified several sites at which we or a predecessor company historically owned or operated a manufactured gas plant. These sites have been substantially remediated or are at various stages of investigation, monitoring and remediation. We have also identified other sites that may have been impacted by historical manufactured gas plant activities. Based upon on-going analysis, we estimate that the future costs for detailed site investigation and future remediation costs may range from $6 million to $12 million over the next ten years . This estimate is dependent upon several variables including, among other things, the extent of remediation, changes in technology and changes in regulation. As of June 30, 2015 , we have established reserves of $6.5 million related to future remediation costs. Historically, the PSCW has allowed Wisconsin utilities, including us, to defer the costs spent on the remediation of manufactured gas plant sites, and has allowed for these costs to be recovered in rates over five years. Accordingly, we have recorded a regulatory asset for remediation costs.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION During the six months ended June 30, 2015 , we paid $56.2 million in interest, net of amounts capitalized, and paid $20.9 million in income taxes, net of refunds. During the six months ended June 30, 2014 , we paid $60.6 million in interest, net of amounts capitalized, and paid $12.0 million in income taxes, net of refunds. As of June 30, 2015 and 2014 , the amount of accounts payable related to capital expenditures was $3.4 million and $3.1 million , respectively. During the six months ended June 30, 2015 and 2014 , our equity in earnings from ATC was $26.4 million and $30.5 million , respectively. During the six months ended June 30, 2015 and 2014 , distributions received from ATC were $18.6 million and $25.0 million , respectively.

Michigan Settlement (Notes)

Michigan Settlement (Notes)	6 Months Ended
	Jun. 30, 2015
Michigan Settlement [Abstract]
Michigan Settlement Disclosure [Text Block]	MICHIGAN SETTLEMENT In March 2015, we, along with Wisconsin Energy, entered into an Amended and Restated Settlement Agreement (Amended Agreement) with the Attorney General of the State of Michigan, the Staff of the MPSC, and Tilden Mining Company and Empire Iron Mining Partnership to resolve all objections to Wisconsin Energy's acquisition of Integrys these parties raised at the MPSC. The agreement includes the following provisions: • The parties to the Amended Agreement agree that the acquisition satisfies the applicable requirements under Michigan law and should be approved by the MPSC. • We will not enter into a System Support Resource (SSR) agreement for the operation of Presque Isle Power Plant (PIPP) so long as both mines, if operational, remain full requirements customers of ours until the earlier of (i) the date a new, clean generation plant located in the Upper Peninsula of Michigan commences commercial operation or (ii) December 31, 2019. (The prior SSR agreement was terminated effective February 1, 2015 with the return of the mines as full requirements customers.) • Wisconsin Energy commits to invest either through an ownership interest or a purchased power agreement, or to have, if formed, a future Michigan jurisdictional utility invest, in this plant subject to the issuance of a Certificate of Necessity from the MPSC. The costs of this plant would be recovered from Michigan customers. In addition, in March 2015, we entered into a special contract with each of the mines to provide full requirements electric service through December 31, 2019. In April 2015, the MPSC approved the acquisition of Integrys, the Amended Agreement and the special contracts with the two mines.

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Description of New Accounting Pronouncements Not yet Adopted [Text Block]	NEW ACCOUNTING PRONOUNCEMENTS Revenue Recognition: In May 2014, the Financial Accounting Standards Board (FASB) and the International Accounting Standards Board issued their joint revenue recognition standard, Accounting Standards Update 2014-09, Revenue from Contracts with Customers. The guidance is based on the principle that revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. This guidance is effective for fiscal years and interim periods beginning after December 15, 2017, with early adoption for fiscal years and interim periods beginning after December 15, 2016 permitted. The standard can either be applied retrospectively or as a cumulative-effect adjustment as of the date of adoption. We are currently assessing the effects this guidance may have on our consolidated financial statements. Debt Issuance Costs: In April 2015, the FASB issued Accounting Standards Update 2015-03, Simplifying the Presentation of Debt Issuance Costs. The guidance requires debt issuance costs to be presented on the balance sheet as a reduction to the carrying value of the corresponding debt, rather than as an asset as it is currently presented. This guidance is effective for fiscal years and interim periods beginning after December 15, 2015. The standard requires retrospective application by restating each prior period presented in the financial statements. We are currently assessing the effects this guidance may have on our consolidated financial statements.

Common Equity (Tables)

Common Equity (Tables)	6 Months Ended
	Jun. 30, 2015
Stockholders' Equity Note [Abstract]
Assumptions for valuing options using binomial option pricing model	2015 2014 Non-qualified stock options granted year to date 495,550 864,860 Estimated fair value per non-qualified stock option $ 5.29 $ 4.18 Assumptions used to value the options using a binomial option pricing model: Risk-free interest rate 0.1% - 2.1% 0.1% - 3.0% Dividend yield 3.7 % 3.8 % Expected volatility 18.0 % 18.0 % Expected forfeiture rate 2.0 % 2.0 % Expected life (years) 5.8 5.8
Stock option activity	Weighted- Average Weighted- Remaining Aggregate Number of Average Contractual Life Intrinsic Value Stock Options Options Exercise Price (Years) (Millions) Outstanding as of April 1, 2015 6,607,682 $ 32.11 Granted — $ — Exercised (174,369 ) $ 21.07 Outstanding as of June 30, 2015 6,433,313 $ 32.41 Outstanding as of January 1, 2015 6,450,277 $ 30.07 Granted 495,550 $ 52.90 Exercised (512,514 ) $ 22.82 Outstanding as of June 30, 2015 6,433,313 $ 32.41 5.7 $ 80.8 Exercisable as of June 30, 2015 3,800,683 $ 26.10 4.0 $ 71.7
Stock options outstanding	Options Outstanding Options Exercisable Weighted-Average Weighted-Average Remaining Remaining Number of Exercise Contractual Number of Exercise Contractual Range of Exercise Prices Options Price Life (Years) Options Price Life (Years) $19.74 to $21.11 1,169,925 $ 20.99 3.3 1,169,925 $ 20.99 3.3 $23.88 to $29.35 1,786,018 $ 25.17 3.3 1,786,018 $ 25.17 3.3 $34.88 to $52.90 3,477,370 $ 39.96 7.8 844,740 $ 35.15 6.6 6,433,313 $ 32.41 5.7 3,800,683 $ 26.10 4.0
Non-vested options	Weighted-Average Non-Vested Stock Options Number of Options Fair Value Non-vested as of April 1, 2015 2,632,630 $ 4.03 Granted — $ — Vested — $ — Forfeited — $ — Non-vested as of June 30, 2015 2,632,630 $ 4.03 Non-vested as of January 1, 2015 2,767,835 $ 3.65 Granted 495,550 $ 5.29 Vested (630,755 ) $ 3.34 Non-vested as of June 30, 2015 2,632,630 $ 4.03
Restricted stock activity	Weighted-Average Restricted Shares Number of Shares Grant Date Fair Value Outstanding as of April 1, 2015 93,639 Granted — $ — Released — $ — Outstanding as of June 30, 2015 93,639 Outstanding as of January 1, 2015 100,657 Granted 43,212 $ 53.78 Released (50,230 ) $ 37.73 Outstanding as of June 30, 2015 93,639

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Fair Value Measurements (Tables) [Abstract]
Financial assets and liabilities by level within the fair value hierarchy	Recurring Fair Value Measures As of June 30, 2015 Level 1 Level 2 Level 3 Total (Millions of Dollars) Assets: Derivatives $ 1.0 $ 1.3 $ 3.6 $ 5.9 Total $ 1.0 $ 1.3 $ 3.6 $ 5.9 Liabilities: Derivatives $ 2.9 $ 4.7 $ — $ 7.6 Total $ 2.9 $ 4.7 $ — $ 7.6 Recurring Fair Value Measures As of December 31, 2014 Level 1 Level 2 Level 3 Total (Millions of Dollars) Assets: Derivatives $ 0.4 $ 5.2 $ 7.0 $ 12.6 Total $ 0.4 $ 5.2 $ 7.0 $ 12.6 Liabilities: Derivatives $ 6.8 $ 0.5 $ — $ 7.3 Total $ 6.8 $ 0.5 $ — $ 7.3
Fair value of derivatives classified as Level 3 in the fair value hierarchy		Three Months Ended June 30 Six Months Ended June 30 2015 2014 2015 2014 (Millions of Dollars) Beginning Balance $ 3.3 $ 1.7 $ 7.0 $ 3.5 Realized and unrealized gains (losses) — — — — Purchases 3.9 15.6 3.9 15.6 Issuances — — — — Settlements (3.6 ) (3.2 ) (7.3 ) (5.0 ) Transfers in and/or out of Level 3 — — — — Balance as of June 30 $ 3.6 $ 14.1 $ 3.6 $ 14.1
Carrying amount and estimated fair value of certain financial instruments	June 30, 2015 December 31, 2014 Financial Instruments Carrying Amount Fair Value Carrying Amount Fair Value (Millions of Dollars) Preferred stock, no redemption required $ 30.4 $ 27.0 $ 30.4 $ 27.1 Long-term debt, including current portion $ 2,687.0 $ 2,619.1 $ 2,437.0 $ 2,759.6

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments (Tables) [Abstract]
Derivative instruments in balance sheet	June 30, 2015 December 31, 2014 Derivative Asset Derivative Liability Derivative Asset Derivative Liability (Millions of Dollars) Natural Gas $ 0.9 $ 2.9 $ 2.3 $ 7.1 Fuel Oil 0.1 — — — FTRs 3.6 — 7.0 — Coal 1.3 4.7 3.3 0.2 Total $ 5.9 $ 7.6 $ 12.6 $ 7.3
Derivative instruments' estimated notional volumes and gain (losses)	Three Months Ended June 30, 2015 Three Months Ended June 30, 2014 Volume Gains (Losses) Volume Gains (Losses) (Millions of Dollars) (Millions of Dollars) Natural Gas 5.9 million Dth $ (3.1 ) 5.4 million Dth $ 1.5 Fuel Oil 0.8 million gallons 0.1 2.4 million gallons 0.4 FTRs 5.9 million MWh 0.8 7.4 million MWh 2.6 Total $ (2.2 ) $ 4.5 Six Months Ended June 30, 2015 Six Months Ended June 30, 2014 Volume Gains (Losses) Volume Gains (Losses) (Millions of Dollars) (Millions of Dollars) Natural Gas 12.3 million Dth $ (6.9 ) 12.6 million Dth $ 5.4 Fuel Oil 1.7 million gallons — 4.4 million gallons 0.6 FTRs 12.1 million MWh 2.9 13.1 million MWh 9.6 Total $ (4.0 ) $ 15.6
Offsetting Assets and Liabilities [Table Text Block]	June 30, 2015 December 31, 2014 Derivative Derivative Derivative Derivative Asset Liability Asset Liability (Millions of Dollars) Gross Amount Recognized on the Balance Sheet $ 5.9 $ 7.6 $ 12.6 $ 7.3 Gross Amount Not Offset on Balance Sheet (a) (0.9 ) (2.9 ) (0.4 ) (6.8 ) Net Amount $ 5.0 $ 4.7 $ 12.2 $ 0.5 (a) Gross Amount Not Offset on Balance Sheet includes cash collateral posted of $2.0 million and $6.4 million as of June 30, 2015 and December 31, 2014 , respectively.

Benefits (Tables)

Benefits (Tables)	6 Months Ended
	Jun. 30, 2015
Benefits (Tables) [Abstract]
Components of net periodic pension and OPEB costs	Pension Costs Three Months Ended June 30 Six Months Ended June 30 Benefit Plan Cost Components 2015 2014 2015 2014 (Millions of Dollars) Net Periodic Benefit Cost Service cost $ 3.6 $ 2.2 $ 7.3 $ 4.7 Interest cost 13.1 14.9 26.4 29.7 Expected return on plan assets (20.8 ) (19.8 ) (41.8 ) (39.6 ) Amortization of: Prior service cost 0.5 0.5 1.0 1.0 Actuarial loss 8.9 6.9 17.9 13.5 Net Periodic Benefit Cost $ 5.3 $ 4.7 $ 10.8 $ 9.3 OPEB Costs Three Months Ended June 30 Six Months Ended June 30 Benefit Plan Cost Components 2015 2014 2015 2014 (Millions of Dollars) Net Periodic Benefit Cost Service cost $ 2.1 $ 1.9 $ 4.5 $ 4.0 Interest cost 3.3 3.6 6.7 7.2 Expected return on plan assets (4.0 ) (4.1 ) (8.0 ) (8.1 ) Amortization of: Prior service credit (0.3 ) (0.4 ) (0.6 ) (0.8 ) Actuarial loss 0.3 0.1 0.6 0.1 Net Periodic Benefit Cost $ 1.4 $ 1.1 $ 3.2 $ 2.4

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting Information [Line Items]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Reportable Segments Electric Gas Steam Total (Millions of Dollars) Three Months Ended June 30, 2015 Operating Revenues (a) $ 813.5 $ 61.3 $ 8.2 $ 883.0 Operating Income $ 122.4 $ 6.4 $ (0.1 ) $ 128.7 June 30, 2014 Operating Revenues (a) $ 813.7 $ 83.8 $ 8.2 $ 905.7 Operating Income $ 135.3 $ 8.5 $ 0.4 $ 144.2 Six Months Ended June 30, 2015 Operating Revenues (a) $ 1,682.4 $ 259.2 $ 26.0 $ 1,967.6 Operating Income $ 281.2 $ 45.1 $ 7.1 $ 333.4 June 30, 2014 Operating Revenues (a) $ 1,699.5 $ 406.3 $ 26.6 $ 2,132.4 Operating Income $ 304.2 $ 53.9 $ 7.9 $ 366.0 (a) We account for all intersegment revenues at rates established by the PSCW. Intersegment revenues were not material.

Acquisition (Details)

Acquisition (Details) - $ / shares	1 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 29, 2015
Business Combinations [Abstract]
Percentage of Integrys common shares acquired			100.00%
Equity Method Investment, Ownership Percentage	60.00%	60.00%
Number of WEC shares per Integrys share		1.128
Cash per share of Integrys common stock	$ 18.58
Duration of earnings cap condition imposed by the PSCW	3 years

Common Equity (Details)

Common Equity (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014
Performance units [Member]
Common Equity (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		187,450	224,735
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value		$ 11.6	$ 13.1
Tax Benefit from Stock Options Exercised		4.2	4.7
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 12.3	$ 12.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		23 months
Restricted stock [Member]
Common Equity (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	43,212
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value		$ 2.7	2.3
Tax Benefit from Stock Options Exercised			$ 0.9
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 3.3	$ 3.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		24 months

Common Equity 1 (Details)

Common Equity 1 (Details) - $ / shares	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		3.70%	3.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		18.00%	18.00%
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Forfeiture Rate		2.00%	2.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term		5 years 9 months	5 years 9 months
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	0	495,550	864,860
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 5.29	$ 4.18
Lower Range [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		0.10%	0.10%
Upper Range [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		2.10%	3.00%

Common Equity 2 (Details)

Common Equity 2 (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6,433,313		6,433,313
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 32.41		$ 32.41
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	3,800,683		3,800,683
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 26.10		$ 26.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term			4 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 4.7	$ 2	$ 14.6	$ 15.9
Proceeds from Stock Options Exercised			11.7	16.2
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			$ 5.9	$ 6.5
Stock options [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6,607,682		6,450,277
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period	0		495,550	864,860
Share Based Compensation Arrangement By Share Based Payment Award Options Grant In Period Weighted Average Exercise Price	$ 0		$ 52.90
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	(174,369)		(512,514)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6,433,313		6,433,313
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 32.11		$ 30.07
Share Based Compensation Arrangement By Share Based Payment Awards Options Exercises In Period Weighted Average Exercise Price	21.07		22.82
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 32.41		$ 32.41
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Remaining Contractual Period			5 years 8 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 80.8		$ 80.8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	3,800,683		3,800,683
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 26.10		$ 26.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term			4 years
Share Based Compensation Arrangement by Share Based Payments Award, Options Exercisable, Intrinsic Value	$ 71.7		$ 71.7

Common Equity 3 (Details)

Common Equity 3 (Details) - Jun. 30, 2015 - $ / shares	Total
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6,433,313
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 32.41
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	5 years 8 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	3,800,683
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 26.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	4 years
Exercise Price, Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	1,169,925
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 20.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 3 months
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	1,169,925
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 20.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	3 years 3 months
Exercise Price, Range One [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 19.74
Exercise Price, Range One [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 21.11
Exercise Price, Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	1,786,018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 25.17
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 3 months
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	1,786,018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 25.17
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	3 years 3 months
Exercise Price, Range Two [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 23.88
Exercise Price, Range Two [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 29.35
Exercise Price, Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	3,477,370
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 39.96
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	7 years 9 months
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	844,740
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 35.15
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	6 years 7 months
Exercise Price, Range Three [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 34.88
Exercise Price, Range Three [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 52.90

Common Equity 4 (Details)

Common Equity 4 (Details) - Jun. 30, 2015 - USD ($) $ / shares in Units, $ in Millions	Total	Total
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6,433,313	6,433,313
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 32.41	$ 32.41
Performance units [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		23 months
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 12.3	$ 12.3
Non Vested Options [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	2,632,630	2,767,835
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period	0	495,550
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period	0	(630,755)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	2,632,630	2,632,630
Non-vested options outstanding beginning balance, weighted average fair value	$ 4.03	$ 3.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	0	5.29
Share Based Compensation Arrangements By Share Based Payment Awards Options Vested In Period Weighted Average Fair Value	0	3.34
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Intrinsic Value	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 4.03	$ 4.03
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		18 months
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 3.1	$ 3.1

Common Equity 5 (Details)

Common Equity 5 (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation		$ 5.9	$ 6.5
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Share Based Compensation Arrangement By Share Based Payment Award Award Percentage To Vest Each Year After Grant Date		33.00%
Performance units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value		$ 11.6	$ 13.1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		187,450	224,735
Tax Benefit from Stock Options Exercised		$ 4.2	$ 4.7
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 12.3	$ 12.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		23 months
Restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value		$ 2.7	2.3
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation		$ 1.1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	93,639	100,657
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	43,212
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	0	(50,230)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	93,639	93,639
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0	$ 53.78
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 0	$ 37.73
Tax Benefit from Stock Options Exercised			$ 0.9
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 3.3	$ 3.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		24 months

Long Term Debt (Details)

Long Term Debt (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015
Wis Elec Debenture due June 1, 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 250
Debt Instrument, Interest Rate, Stated Percentage		3.10%
Wis Elec Debenture due June 1, 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250
Debt Instrument, Interest Rate, Stated Percentage	4.25%
Wis Elec Debentures due April 1, 2014 [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount	$ 300

Fair Value Measurements Assets

Fair Value Measurements Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value, Assets Measured on Recurring Basis, Derivative Financial Instruments, Assets	$ 1	$ 0.4
Fair Value Assets Measured on Recurring Basis Total Assets	1	0.4
Fair Value, Liabilities Measured on Recurring Basis, Derivative Financial Instruments, Liabilities	2.9	6.8
Fair Value Liabilities Measured on Recurring Basis Total Liabilities	2.9	6.8
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value, Assets Measured on Recurring Basis, Derivative Financial Instruments, Assets	1.3	5.2
Fair Value Assets Measured on Recurring Basis Total Assets	1.3	5.2
Fair Value, Liabilities Measured on Recurring Basis, Derivative Financial Instruments, Liabilities	4.7	0.5
Fair Value Liabilities Measured on Recurring Basis Total Liabilities	4.7	0.5
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value, Assets Measured on Recurring Basis, Derivative Financial Instruments, Assets	3.6	7
Fair Value Assets Measured on Recurring Basis Total Assets	3.6	7
Fair Value, Liabilities Measured on Recurring Basis, Derivative Financial Instruments, Liabilities	0	0
Fair Value Liabilities Measured on Recurring Basis Total Liabilities	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair Value, Assets Measured on Recurring Basis, Derivative Financial Instruments, Assets	5.9	12.6
Fair Value Assets Measured on Recurring Basis Total Assets	5.9	12.6
Fair Value, Liabilities Measured on Recurring Basis, Derivative Financial Instruments, Liabilities	7.6	7.3
Fair Value Liabilities Measured on Recurring Basis Total Liabilities	$ 7.6	$ 7.3

Fair Value Measurements, Deriva

Fair Value Measurements, Derivatives (Details) - Derivative [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair value of derivatives classified as Level 3 in the fair value hierarchy
Beginning Balance	$ 3.3	$ 1.7	$ 7	$ 3.5
Realized and unrealized gains (losses)	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	3.9	15.6	3.9	15.6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(3.6)	(3.2)	(7.3)	(5)
Transfers in and/or out of Level 3	0	0	0	0
Ending Balance	$ 3.6	$ 14.1	$ 3.6	$ 14.1

Fair Value Measurements, Financ

Fair Value Measurements, Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Financial Instruments
Preferred stock	$ 30.4	$ 30.4
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Financial Instruments
Preferred stock	30.4	30.4
Long-term debt including current portion	2,687	2,437
Estimate of Fair Value, Fair Value Disclosure [Member]
Financial Instruments
Preferred stock	27	27.1
Long-term debt including current portion	$ 2,619.1	$ 2,759.6

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative asset	$ 5,900,000		$ 5,900,000		$ 12,600,000
Derivative liability	7,600,000		7,600,000		7,300,000
Gains (losses)	(2,200,000)	$ 4,500,000	(4,000,000)	$ 15,600,000
Derivative Instruments (Textuals)
Collateral in margin accounts	4,400,000		4,400,000		6,900,000
Other Deferred Charges and Other Assets [Member]
Derivatives, Fair Value [Line Items]
Long-term portion of derivative assets	0		0
Other Deferred Credits and Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Long-term portion of derivative liabilities	200,000		200,000
Natural Gas [Member]
Derivatives, Fair Value [Line Items]
Derivative asset	900,000		900,000		2,300,000
Derivative liability	$ 2,900,000		$ 2,900,000		7,100,000
Volume of derivative instruments	5.9 million Dth	5.4 million Dth	12.3 million Dth	12.6 million Dth
Gains (losses)	$ (3,100,000)	$ 1,500,000	$ (6,900,000)	$ 5,400,000
Fuel Oil [Member]
Derivatives, Fair Value [Line Items]
Derivative asset	100,000		100,000		0
Derivative liability	$ 0		$ 0		0
Volume of derivative instruments	0.8 million gallons	2.4 million gallons	1.7 million gallons	4.4 million gallons
Gains (losses)	$ 100,000	$ 400,000	$ 0	$ 600,000
Ftrs [Member]
Derivatives, Fair Value [Line Items]
Derivative asset	3,600,000		3,600,000		7,000,000
Derivative liability	$ 0		$ 0		0
Volume of derivative instruments	5.9 million MWh	7.4 million MWh	12.1 million MWh	13.1 million MWh
Gains (losses)	$ 800,000	$ 2,600,000	$ 2,900,000	$ 9,600,000
Coal [Member]
Derivatives, Fair Value [Line Items]
Derivative asset	1,300,000		1,300,000		3,300,000
Derivative liability	$ 4,700,000		$ 4,700,000		$ 200,000

Derivative Instruments (Detai36

Derivative Instruments (Details 1) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivative [Member]
Regulatory Assets [Line Items]
Regulatory assets related to derivatives	$ 7.4	$ 8.4

Derivative Instruments (Detai37

Derivative Instruments (Details 2) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivative [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities related to derivatives	$ 4.9	$ 12.2

Derivative Instruments Derivati

Derivative Instruments Derivative Instruments (Details 3) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 4,400,000	$ 6,900,000
Derviative Instrument by Counterparty, Gross Amount Recognized on Balance Sheet [Member]
Derivative [Line Items]
Derivative Assets	5,900,000	12,600,000
Derivative Liabilities	7,600,000	7,300,000
Derviative Instrument by Counterparty, Gross Amount Not Offset on Balance Sheet [Member] [Member]
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	2,000,000	6,400,000
Derivative Assets	(900,000)	(400,000)
Derivative Liabilities	(2,900,000)	(6,800,000)
Derviative Instrument by Counterparty, Net Amount [Member]
Derivative [Line Items]
Derivative Assets	5,000,000	12,200,000
Derivative Liabilities	$ 4,700,000	$ 500,000

Benefits (Details)

Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Benefits (Textuals) [Abstract]
Pension and Other Postretirement Benefit Contributions		$ 0	$ 100	$ 0
Estimated liability of Postemployment benefits	$ 1.8		1.8		$ 1.8
Pension Plans, Defined Benefit [Member]
Net Periodic Benefit Cost
Service cost	3.6	2.2	7.3	4.7
Interest cost	13.1	14.9	26.4	29.7
Expected return on plan assets	(20.8)	(19.8)	(41.8)	(39.6)
Amortization of:
Prior service cost (credit)	0.5	0.5	1	1
Actuarial loss	8.9	6.9	17.9	13.5
Net Periodic Benefit Cost	5.3	4.7	10.8	9.3
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net Periodic Benefit Cost
Service cost	2.1	1.9	4.5	4
Interest cost	3.3	3.6	6.7	7.2
Expected return on plan assets	(4)	(4.1)	(8)	(8.1)
Amortization of:
Prior service cost (credit)	(0.3)	(0.4)	(0.6)	(0.8)
Actuarial loss	0.3	0.1	0.6	0.1
Net Periodic Benefit Cost	$ 1.4	$ 1.1	$ 3.2	$ 2.4

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Operating Revenues	[1]	$ 883	$ 905.7	$ 1,967.6	$ 2,132.4
Operating Income (Loss)		128.7	144.2	333.4	366
Reportable Operating Segment Electric [Member]
Segment Reporting Information [Line Items]
Operating Revenues	[1]	813.5	813.7	1,682.4	1,699.5
Operating Income (Loss)		122.4	135.3	281.2	304.2
Reportable Operating Segment Gas [Member]
Segment Reporting Information [Line Items]
Operating Revenues	[1]	61.3	83.8	259.2	406.3
Operating Income (Loss)		6.4	8.5	45.1	53.9
Reportable Operating Segment Steam [Member]
Segment Reporting Information [Line Items]
Operating Revenues	[1]	8.2	8.2	26	26.6
Operating Income (Loss)		$ (0.1)	$ 0.4	$ 7.1	$ 7.9
[1]	We account for all intersegment revenues at rates established by the PSCW. Intersegment revenues were not material.

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)
Variable Interest Entity [Line Items]
Power capacity under capital lease (MW)	236
Capital Lease Agreement With Vie Remaining Term In Years	7 years
Total payments over remaining terms of the agreement	$ 152.2
Total capacity and lease payments	$ 26.8	$ 26.7

Commitments and Contingencies (

Commitments and Contingencies (Details) - Jun. 30, 2015 - Manufactured Gas Plant Sites [Member] - USD ($) $ in Millions	Total
Commitments and Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum	$ 6
Loss Contingency, Range of Possible Loss, Maximum	$ 12
Period for future costs of detailed site investigation and remediation costs	over the next ten years
Accrual for Environmental Loss Contingencies, Provision for New Losses	$ 6.5

Supplemental Cash Flow Inform43

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Supplemental Cash Flow Information (Textuals)
Interest paid, net of amounts capitalized			$ 56.2	$ 60.6
Income taxes paid, net of refunds			20.9	12
Accounts payable related to capital expenditures	$ 3.4	$ 3.1	3.4	3.1
Income (Loss) from Equity Method Investments	$ 12.2	$ 15.3	26.4	30.5
Distributions from transmission affiliate			$ 18.6	$ 25