WEC Energy (WEC) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014	Jan. 31, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	WISCONSIN ENERGY CORP
Entity Central Index Key	783325
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$10.60
Entity Common Stock, Shares Outstanding (actual number of shares)		225,506,754

Consolidated_Income_Statements

Consolidated Income Statements (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Revenues	$4,997.10	$4,519	$4,246.40
Operating Expenses
Fuel and purchased power	1,223.30	1,153	1,098.60
Cost of gas sold	1,036.10	674.1	545.8
Other operation and maintenance	1,112.40	1,155	1,116.10
Depreciation and amortization	408.8	388.1	364.2
Property and revenue taxes	121.8	116.7	121.4
Total Operating Expenses	3,902.40	3,486.90	3,246.10
Treasury Grant	17.4	48	0
Operating Income	1,112.10	1,080.10	1,000.30
Income (Loss) from Equity Method Investments	65.9	68.4	65.5
Other Income and Deductions, net	13.4	18.8	34.8
Interest Expense, net	241.5	252.1	248.2
Income (Loss) from Continuing Operations Before Income Taxes	950	915.3	852.6
Total Income Tax Expense, Amount	361.7	337.9	306.3
Net Income	588.3	577.4	546.3
Earnings Per Share (Basic)
Earnings Per Share, Basic	$2.61	$2.54	$2.37
Earnings Per Share (Diluted)
Total Earnings Per Share (Diluted)	$2.59	$2.51	$2.35
Weighted Average Common Shares Outstanding (Millions)
Basic	225.6	227.6	230.2
Diluted	227.5	229.7	232.8
Transmission Affiliate [Member]
Operating Expenses
Income (Loss) from Equity Method Investments	$66	$68.50	$65.70

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Property, Plant and Equipment
In service	$15,509		$14,966.30
Accumulated depreciation	-4,485.10		-4,257.10
In service, net	11,023.90		10,709.20
Construction work in progress	191.8		149.6
Leased facilities, net	42		47.8
Net Property, Plant and Equipment	11,257.70		10,906.60
Investments
Equity investment in transmission affiliate	424.1		402.7
Other	32.8		36.1
Total Investments	456.9		438.8
Current Assets
Cash and cash equivalents	61.9		26
Accounts receivable, net of allowance for doubtful accounts of $74.5 and $61.0	352.1		406
Accrued revenues	291.3		321.1
Materials, supplies and inventories	400.6		329.4
Deferred Tax Assets, Net, Current	242.7		310
Prepayments	148.2		145.7
Other	38.6		12.9
Total Current Assets	1,535.40		1,551.10
Deferred Charges and Other Assets
Regulatory assets	1,271.20		1,108.50
Goodwill	441.9		441.9
Other	200.3		322.5
Total Deferred Charges and Other Assets	1,913.40		1,872.90
Total Assets	15,163.40	[1]	14,769.40	[1]
Capitalization
Common equity	4,419.70		4,233
Preferred Stock	30.4		30.4
Long-term debt	4,186.40		4,363.20
Total Capitalization	8,636.50		8,626.60
Current Liabilities
Long-term debt due currently	424.1		342.2
Short-term debt	617.6		537.4
Accounts payable	363.3		342.6
Accrued payroll and benefits	95.1		96.9
Other	168.6		177.3
Total Current Liabilities	1,668.70		1,496.40
Deferred Credits and Other Liabilities
Regulatory liabilities	830.6		879.1
Deferred income taxes - long-term	2,906.70		2,634
Deferred revenue, net	614.1		664.2
Pension and other benefit obligations	203.8		173.2
Other long-term liabilities	303		295.9
Total Deferred Credits and Other Liabilities	4,858.20		4,646.40
Commitments and Contingencies (Note Q)
Total Capitalization and Liabilities	$15,163.40		$14,769.40
[1]	An elimination of $2,172.9 million, $2,231.2 million and $2,286.7 million is included in Total Assets as of December 31, 2014, 2013 and 2012, respectively, for all PTF-related activity between We Power and Wisconsin Electric.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current Assets
Allowance on accounts receivable	$74.50	$61

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities
Net income	$588.30	$577.40	$546.30
Reconciliation to cash
Depreciation and amortization	419.4	400.2	371.7
Deferred income taxes and investment tax credits, net	328.1	312.7	293.2
Contributions to qualified benefit plans	0	0	-100
Change in -
Accounts receivable and accrued revenues	80.7	-162.9	38.3
Inventories	-71.2	31.3	21.3
Other current assets	-13.9	2.8	12.1
Accounts payable	23.7	-14.8	43.8
Accrued income taxes, net	-11.4	36.6	116.9
Deferred costs, net	-15.1	-8.7	9.2
Other current liabilities	-18.8	7.2	-14.9
Other, net	-112.1	49.2	-164
Cash Provided by Operating Activities	1,197.70	1,231	1,173.90
Investing Activities
Capital expenditures	-736.1	-687.4	-707
Investment in transmission affiliate	-13.1	-10.5	-15.7
Proceeds from asset sales	13.9	2.5	8.7
Change in restricted cash	0	2.7	42.8
Payments for (Proceeds from) Removal Costs	-25.1	-37.8	-38.3
Other, net	3.6	-15.3	-20.1
Cash Used in Investing Activities	-756.8	-745.8	-729.6
Financing Activities
Exercise of stock options	50.3	48.5	49.8
Purchase of common stock	-123.2	-223.4	-153.2
Dividends paid on common stock	-352	-328.9	-276.3
Issuance of long-term debt	250	251	251.8
Retirement and repurchase of long-term debt	-324.3	-397.2	-20.3
Change in short-term debt	80.2	142.8	-275.3
Other, net	14	12.4	0.7
Cash Used in Financing Activities	-405	-494.8	-422.8
Change in Cash and Cash Equivalents	35.9	-9.6	21.5
Cash and Cash Equivalents at Beginning of Year	26	35.6	14.1
Cash and Cash Equivalents at End of Year	$61.90	$26	$35.60

Consolidated_Statements_of_Com

Consolidated Statements of Common Equity (USD $)	Total	Common Stock [Member]	Other Paid In Capital [Member]	Retained Earnings [Member]
In Millions
Beginning - Balance at Dec. 31, 2011	$3,963.30	$2.30	$598.50	$3,362.50
Net income	546.3			546.3
Common stock cash dividends of $1.20, $1.445, and $1.56 per share for Year ended 2012, 2013 and 2014, respectively	-276.3			-276.3
Exercise of stock options	49.8		49.8
Purchase of common stock	-153.2		-153.2
Stock-based compensation and other	5.2		5.2
Ending - Balance at Dec. 31, 2012	4,135.10	2.3	500.3	3,632.50
Net income	577.4			577.4
Common stock cash dividends of $1.20, $1.445, and $1.56 per share for Year ended 2012, 2013 and 2014, respectively	-328.9			-328.9
Exercise of stock options	48.5		48.5
Purchase of common stock	-223.4		-223.4
Tax benefit from share based compensation	18.1		18.1
Stock-based compensation and other	6.2		6.2
Ending - Balance at Dec. 31, 2013	4,233	2.3	349.7	3,881
Net income	588.3			588.3
Common stock cash dividends of $1.20, $1.445, and $1.56 per share for Year ended 2012, 2013 and 2014, respectively	-352			-352
Exercise of stock options	50.3		50.3
Purchase of common stock	-123.2		-123.2
Tax benefit from share based compensation	16.8		16.8
Stock-based compensation and other	6.5		6.5
Ending - Balance at Dec. 31, 2014	$4,419.70	$2.30	$300.10	$4,117.30

Consolidated_Statements_of_Com1

Consolidated Statements of Common Equity (Parenthetical) (Retained Earnings [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Retained Earnings [Member]
Common stock cash dividends per share	$1.56	$1.45	$1.20

Consolidated_Statements_of_Cap

Consolidated Statements of Capitalization (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Common Equity	$4,419.70		$4,233
Preferred Stock	30.4		30.4
Obligations under capital leases	84.5		104.3
Unamortized discount, net and other	-26.4		-25.6
Long-term debt due currently	-424.1		-342.2
Total Long-Term Debt	4,186.40		4,363.20
Total Capitalization	8,636.50		8,626.60
Debentures (unsecured), 6.00% due 2014 [Member]
Long-Term debt, Unsecured	0		300
Debentures (unsecured), 5.20% due 2015 [Member]
Long-Term debt, Unsecured	125		125
Debentures (unsecured), 6.25% due 2015 [Member]
Long-Term debt, Unsecured	250		250
Debentures (unsecured), 1.70% due 2018 [Member]
Long-Term debt, Unsecured	250		250
Debentures (unsecured), 4.25% due 2019 [Member]
Long-Term debt, Unsecured	250		250
Debentures (unsecured) 2.95% due 2021 [Member]
Long-Term debt, Unsecured	300		300
Debentures (unsecured), 6-1/2% due 2028 [Member]
Long-Term debt, Unsecured	150		150
Debentures (unsecured), 5.625% due 2033 [Member]
Long-Term debt, Unsecured	335		335
Debentures (unsecured), 5.90% due 2035 [Member]
Long-Term debt, Unsecured	90		90
Notes (secured, nonrecourse), 4.91% due 2014-2030 [Member] [Member]
Long-Term debt, Secured	117.2	[1]	122.1	[1]
Debentures (unsecured), 5.70% due 2036 [Member]
Long-Term debt, Unsecured	300		300
Debentures (unsecured), 3.65% due 2042 [Member]
Long-Term debt, Unsecured	250		250
Debentures (unsecured), 4.25% due 2044 [Member]
Long-Term debt, Unsecured	250		0
Debentures (unsecured), 6-7/8% due 2095 [Member]
Long-Term debt, Unsecured	100		100
Notes (secured, nonrecourse), 4.81% effective rate due 2030 [Member]
Long-Term debt, Secured	2		2
Notes (secured, nonrecourse), 5.209% due 2014-2030 [Member] [Member]
Long-Term debt, Secured	223.9	[2]	231.5	[2]
Notes (secured, nonrecourse), 4.673% due 2014-2031 [Member] [Member]
Long-Term debt, Secured	184.7	[2]	190.9	[2]
Notes (secured, nonrecourse), 6.00% due 2014-2033 [Member] [Member]
Long-Term debt, Secured	134.6	[1]	138.4	[1]
Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Long-Term debt, Secured	275	[2]	275	[2]
Notes (secured, nonrecourse), 5.848% due 2031-2041 [Member]
Long-Term debt, Secured	215	[2]	215	[2]
Notes (secured, nonrecourse) 6.00% due 2021 [Member]
Long-Term debt, Secured	0		1.8
Notes (unsecured), 6.94% due 2028 [Member]
Long-Term debt, Unsecured	50		50
Notes (unsecured), 6.20% due 2033 [Member]
Long-Term debt, Unsecured	200		200
Junior Notes (unsecured), 6.25% due 2067 [Member]
Long-Term debt, Unsecured	500		500
Wisconsin Energy Corporation [Member]
Preferred Stock	0		0
Wisconsin Electric [Member]
Preferred Stock	30.4		30.4
Long-Term debt, Unsecured	147
Six Per Cent. Preferred Stock [Member]
Preferred Stock	4.4
Six Per Cent. Preferred Stock [Member] | Wisconsin Electric [Member]
Preferred Stock			4.4
Serial preferred stock, 3.60% Series Redeemable [Member]
Preferred Stock	26
Serial preferred stock, 3.60% Series Redeemable [Member] | Wisconsin Electric [Member]
Preferred Stock			26
Serial preferred stock, $25 par value; authorized 5,000,000 shares; none outstanding [Member]
Preferred Stock	0
Serial preferred stock, $25 par value; authorized 5,000,000 shares; none outstanding [Member] | Wisconsin Electric [Member]
Preferred Stock			$0
[1]	(a) Senior notes are secured by a collateral assignment of the leases between PWGS and Wisconsin Electric related to PWGS 1 and 2.
[2]	(b) Senior notes are secured by a collateral assignment of the leases between ERGSS and Wisconsin Electric related to OC 1 and 2.

Consolidated_Statements_of_Cap1

Consolidated Statements of Capitalization (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Debentures (unsecured), 6.00% due 2014 [Member]
Debt instrument stated interest rate (percentage)	6.00%	6.00%
Debentures (unsecured), 5.20% due 2015 [Member]
Debt instrument stated interest rate (percentage)	5.20%	5.20%
Debentures (unsecured), 6.25% due 2015 [Member]
Debt instrument stated interest rate (percentage)	6.25%	6.25%
Debentures (unsecured), 1.70% due 2018 [Member]
Debt instrument stated interest rate (percentage)	1.70%	1.70%
Debentures (unsecured), 4.25% due 2019 [Member]
Debt instrument stated interest rate (percentage)	4.25%	4.25%
Debentures (unsecured) 2.95% due 2021 [Member]
Debt instrument stated interest rate (percentage)	2.95%	2.95%
Debentures (unsecured), 6-1/2% due 2028 [Member]
Debt instrument stated interest rate (percentage)	6.50%	6.50%
Debentures (unsecured), 5.625% due 2033 [Member]
Debt instrument stated interest rate (percentage)	5.63%	5.63%
Debentures (unsecured), 5.90% due 2035 [Member]
Debt instrument stated interest rate (percentage)	5.90%	5.90%
Debentures (unsecured), 5.70% due 2036 [Member]
Debt instrument stated interest rate (percentage)	5.70%	5.70%
Debentures (unsecured), 3.65% due 2042 [Member]
Debt instrument stated interest rate (percentage)	3.65%	3.65%
Debentures (unsecured), 4.25% due 2044 [Member]
Debt instrument stated interest rate (percentage)	4.25%	4.25%
Debentures (unsecured), 6-7/8% due 2095 [Member]
Debt instrument stated interest rate (percentage)	6.88%	6.88%
Notes (secured, nonrecourse), 4.81% effective rate due 2030 [Member]
Debt instrument stated interest rate (percentage)	4.81%	4.81%
Notes (secured, nonrecourse), 4.91% due 2014-2030 [Member] [Member]
Debt instrument stated interest rate (percentage)	4.91%	4.91%
Notes (secured, nonrecourse), 5.209% due 2014-2030 [Member] [Member]
Debt instrument stated interest rate (percentage)	5.21%	5.21%
Notes (secured, nonrecourse), 4.673% due 2014-2031 [Member] [Member]
Debt instrument stated interest rate (percentage)	4.67%	4.67%
Notes (secured, nonrecourse), 6.00% due 2014-2033 [Member] [Member]
Debt instrument stated interest rate (percentage)	6.00%	6.00%
Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Debt instrument stated interest rate (percentage)	6.09%	6.09%
Notes (secured, nonrecourse), 5.848% due 2031-2041 [Member]
Debt instrument stated interest rate (percentage)	5.85%	5.85%
Notes (secured, nonrecourse) 6.00% due 2021 [Member]
Debt instrument stated interest rate (percentage)	6.00%	6.00%
Notes (unsecured), 6.94% due 2028 [Member]
Debt instrument stated interest rate (percentage)	6.94%	6.94%
Notes (unsecured), 6.20% due 2033 [Member]
Debt instrument stated interest rate (percentage)	6.20%	6.20%
Junior Notes (unsecured), 6.25% due 2067 [Member]
Debt instrument stated interest rate (percentage)	6.25%	6.25%
Wisconsin Energy Corporation [Member]
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, shares outstanding	0	0
Six Per Cent. Preferred Stock [Member]
Preferred stock, shares authorized	45,000
Preferred stock, shares outstanding	44,498
Six Per Cent. Preferred Stock [Member] | Wisconsin Electric [Member]
Preferred stock, par value	$100	$100
Preferred stock, shares authorized		45,000
Preferred stock, shares outstanding		44,498
Preferred stock dividend rate, percentage	6.00%	6.00%
Serial preferred stock, 3.60% Series Redeemable [Member]
Preferred stock, shares outstanding	260,000
Serial preferred stock, 3.60% Series Redeemable [Member] | Wisconsin Electric [Member]
Preferred stock, par value	$100	$100
Preferred stock, shares outstanding		260,000
Preferred stock dividend rate, percentage	3.60%	3.60%

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	General:   Our consolidated financial statements include the accounts of Wisconsin Energy Corporation (Wisconsin Energy, the Company, our, we or us), a diversified holding company, as well as our subsidiaries in the following reportable segments:
	•	Utility Energy Segment -- Consisting of Wisconsin Electric and Wisconsin Gas, engaged primarily in the generation of electricity and the distribution of electricity and natural gas; and
	•	Non-Utility Energy Segment -- Consisting primarily of We Power, engaged principally in the ownership of electric power generating facilities for long-term lease to Wisconsin Electric.
	Our Corporate and Other segment includes Wispark, which develops and invests in real estate. We have also eliminated all intercompany transactions from the consolidated financial statements.
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of certain assets and liabilities and disclosure of contingent assets and liabilities at the date of financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Revenues:   We recognize energy revenues on the accrual basis and include estimated amounts for services rendered but not billed.
	Our retail electric rates in Wisconsin are established by the PSCW and include base amounts for fuel and purchased power costs. The electric fuel rules in Wisconsin allow us to defer, for subsequent rate recovery or refund, any under-collection or over-collection of fuel costs that are outside of the symmetrical fuel cost tolerance, which the PSCW set at plus or minus 2% of the approved fuel cost plan. The deferred under-collected amounts are subject to an excess revenues test.
	Our retail gas rates include monthly adjustments which permit the recovery or refund of actual purchased gas costs. We defer any difference between actual gas costs incurred (adjusted for a sharing mechanism) and costs recovered through rates as a current asset or liability. The deferred balance is returned to or recovered from customers at intervals throughout the year.
	We recognize We Power revenues (consisting of the lease payments included in rates and the amortization of the deferred revenue) on a levelized basis over the term of the lease.
	Accounting for MISO Energy Transactions:   The MISO Energy Markets operate under both day-ahead and real-time markets. We record energy transactions in the MISO Energy Markets on a net basis for each hour.
	Other Income and Deductions, Net:   We recorded the following items in Other Income and Deductions, net for the years ended December 31:
	Other Income and Deductions, net		2014			2013				2012
			(Millions of Dollars)
	AFUDC - Equity		$	5.6		$	18.3			$	35.3
	Gain on Property Sales		7.5			0.8				2.7
	Other, net		0.3			(0.3		)		(3.2		)
	Total Other Income and Deductions, net		$	13.4		$	18.8			$	34.8
	Property and Depreciation:   We record property, plant and equipment at cost. Cost includes material, labor, overheads and capitalized interest. Utility property also includes AFUDC - Equity. Additions to and significant replacements of property are charged to property, plant and equipment at cost; minor items are charged to maintenance expense. The cost of depreciable utility property less salvage value is charged to accumulated depreciation when property is retired.
	We recorded the following property in service by segment as of December 31:
	Property In Service		2014			2013
			(Millions of Dollars)
	Utility Energy		$	12,290.70		$	11,779.80
	Non-Utility Energy		3,127.80			3,091.30
	Other		90.5			95.2
	Total		$	15,509.00		$	14,966.30
	Our utility depreciation rates are certified by the PSCW and MPSC and include estimates for salvage value and removal costs. Depreciation as a percent of average depreciable utility plant was 2.9% in 2014, 2013 and 2012.
	We depreciate our We Power assets over the estimated useful life of the various property components. The components have useful lives of between 10 to 45 years for PWGS 1 and PWGS 2, and 10 to 55 years for OC 1 and OC 2.
	Our regulated utilities collect in their rates amounts representing future removal costs for many assets that do not have an associated Asset Retirement Obligation (ARO). We record a regulatory liability on our balance sheet for the estimated amounts we have collected in rates for future removal costs less amounts we have spent in removal activities. This regulatory liability was $741.1 million as of December 31, 2014 and $724.5 million as of December 31, 2013.
	We recorded the following Construction Work in Progress (CWIP) by segment as of December 31:
	CWIP		2014			2013
			(Millions of Dollars)
	Utility Energy		$	170.1		$	132.7
	Non-Utility Energy		21.1			16.5
	Other		0.6			0.4
	Total		$	191.8		$	149.6
	Allowance For Funds Used During Construction - Regulated:   AFUDC is included in utility plant accounts and represents the cost of borrowed funds (AFUDC - Debt) used during plant construction, and a return on stockholders' capital (AFUDC - Equity) used for construction purposes. AFUDC - Debt is recorded as a reduction of interest expense, and AFUDC - Equity is recorded in Other Income and Deductions, net.
	Our regulated utility segment recorded the following AFUDC for the years ended December 31:
		2014			2013				2012
		(Millions of Dollars)
	AFUDC - Debt	$	2.3		$	7.7			$	14.7
	AFUDC - Equity	$	5.6		$	18.3			$	35.3
	Deferred Revenue:   As part of the construction of the PTF electric generating units, we capitalized interest during construction. As allowed under the lease agreements, we were able to collect the carrying costs during the construction of the PTF generating units from our utility customers. The carrying costs that we collected during construction have been recorded as deferred revenue on our balance sheet and we are amortizing the deferred carrying costs to revenue over the individual lease terms.
	Earnings per Common Share:   We compute basic earnings per common share by dividing our net income attributed to common shareholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per common share is computed by dividing net income attributed to common shareholders by the weighted average number of common shares outstanding during the period, adjusted for the exercise and/or conversion of all potentially dilutive securities. Such dilutive securities include in-the-money stock options. All stock options outstanding during 2014, 2013 and 2012 were included in the computation of diluted earnings per share. Anti-dilutive shares are excluded from the calculation.
	Materials, Supplies and Inventories:   Our inventory as of December 31 consists of:
	Materials, Supplies and Inventories		2014			2013
			(Millions of Dollars)
	Fossil Fuel		$	125.6		$	117.7
	Materials and Supplies		150.2			133.9
	Natural Gas in Storage		124.8			77.8
	Total		$	400.6		$	329.4
	Substantially all fossil fuel, materials and supplies, and natural gas in storage inventories are recorded using the weighted-average cost method of accounting.
	Regulatory Accounting:   The economic effects of regulation can result in regulated companies recording costs that have been or are expected to be allowed in the rate-making process in a period different from the period in which the costs would be charged to expense by an unregulated enterprise. When this occurs, costs are deferred as regulatory assets on the balance sheet and expensed in the periods when they are reflected in rates. We defer regulatory assets pursuant to specific or generic orders issued by our regulators. Additionally, regulators can impose regulatory liabilities upon a regulated company for amounts previously collected from customers and for amounts that are expected to be refunded to customers. In general, regulatory assets are recovered in a period between one to eight years. For further information, see Note C.
	Asset Retirement Obligations:   We record a liability for a legal ARO in the period in which it is incurred. When a new legal obligation is recorded, we capitalize the costs of the liability by increasing the carrying amount of the related long-lived asset. We accrete the liability to its present value each period and depreciate the capitalized cost over the useful life of the related asset. At the end of the asset's useful life, we settle the obligation for its recorded amount or incur a gain or loss. As it relates to our regulated operations, we apply regulatory accounting guidance and recognize regulatory assets or liabilities for the timing differences between when we recover legal AROs in rates and when we would recognize these costs. For further information, see Note E.
	Derivative Financial Instruments:   We have derivative physical and financial instruments which we report at fair value. For further information, see Note L.
	Cash and Cash Equivalents:   Cash and cash equivalents include marketable debt securities acquired three months or less from maturity.
	Margin Accounts:   Cash deposited in brokerage accounts for margin requirements is recorded in Other Current Assets on our Consolidated Balance Sheets.
	Goodwill:   Goodwill reflects the cost of an acquisition in excess of the fair values assigned to identifiable net assets acquired. As of December 31, 2014 and 2013, we had $441.9 million of goodwill recorded at the utility energy segment, which related to our acquisition of Wisconsin Gas in 2000.
	Goodwill is not subject to amortization. However, it is subject to fair value-based rules for measuring impairment, and resulting write-downs, if any, are to be reflected in operating expense. Fair value is assessed by considering future discounted cash flows, a comparison of fair value based on public company trading multiples, and merger and acquisition transaction multiples for similar companies. This evaluation utilizes the information available under the circumstances, including reasonable and supportable assumptions and projections. We perform our annual impairment test as of August 31. There was no impairment to the recorded goodwill balance as of our annual 2014 impairment test date.
	Impairment or Disposal of Long Lived Assets:   We carry property, equipment and goodwill related to businesses held for sale at the lower of cost or estimated fair value less cost to sell. As of December 31, 2014, we had no assets classified as Held for Sale. Long-lived assets are tested for recoverability whenever events or changes in circumstances indicate that their carrying value may not be recoverable from the use and eventual disposition of the asset based on the remaining useful life. An impairment loss is recognized when the carrying amount of an asset is not recoverable and exceeds the fair value of the asset. The carrying amount of an asset is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. An impairment loss is measured as the excess of the carrying amount of the asset in comparison to the fair value of the asset.
	Investments:   We account for investments in other affiliated companies in which we do not maintain control using the equity method of accounting. We had a total ownership interest of approximately 26.2% in ATC as of December 31, 2014 and 2013. We are represented by one out of ten ATC board members, each of whom has one vote. Due to the voting requirements, no individual member has more than 10% of the voting control. For further information regarding such investments, see Note P.
	Income Taxes:   We follow the liability method in accounting for income taxes. Accounting guidance for income taxes requires the recording of deferred assets and liabilities to recognize the expected future tax consequences of events that have been reflected in our financial statements or tax returns and the adjustment of deferred tax balances to reflect tax rate changes. We are required to assess the likelihood that our deferred tax assets would expire before being realized. If we conclude that certain deferred tax assets are likely to expire before being realized, a valuation allowance would be established against those assets. GAAP requires that, if we conclude in a future period that it is more likely than not that some or all of the deferred tax assets would be realized before expiration, we reverse the related valuation allowance in that period. Any change to the allowance, as a result of a change in judgment about the realization of deferred tax assets, is reported in income tax expense.
	Investment tax credits associated with regulated operations are deferred and amortized over the life of the assets. We file a consolidated Federal income tax return. Accordingly, we allocate Federal current tax expense benefits and credits to our subsidiaries based on their separate tax computations. For further information, see Note G.
	We recognize interest and penalties accrued related to unrecognized tax benefits in Income Taxes in our Consolidated Income Statements, as well as Regulatory Assets or Regulatory Liabilities in our Consolidated Balance Sheets.
We collect sales and use taxes from our customers and remit these taxes to governmental authorities. These taxes are recorded in our Consolidated Income Statements on a net basis.
Stock Options:   We estimate the fair value of stock options using the binomial pricing model. We report unearned stock-based compensation associated with non-vested restricted stock and performance share awards activity within Other Paid in Capital in our Consolidated Statements of Common Equity. We report excess tax benefits as a financing cash inflow. Historically, all stock options have been granted with an exercise price equal to the fair market value of the common stock on the date of grant and expire no later than 10 years from grant date. For a discussion of the impacts to our Consolidated Financial Statements, see Note H.
The fair value of our stock options was calculated using a binomial option-pricing model using the following weighted-average assumptions:
	2014		2013	2012
Risk-free interest rate	0.1% - 3.0%		0.1% - 1.9%	0.1% - 2.0%
Dividend yield	3.80%		3.70%	3.90%
Expected volatility	18.00%		18.00%	19.00%
Expected life (years)	5.8		5.9	5.9
Expected forfeiture rate	2.00%		2.00%	2.00%
Weighted-average fair value
of our stock options granted	$4.18		$3.45	$3.34
Treasury Grant:   In December 2013, we filed an application with the United States Treasury for a Section 1603 renewable energy grant related to the construction of our biomass facility in Rothschild, Wisconsin. The PSCW anticipated the recognition of this grant as income when it set rates for the two years beginning January 1, 2013. We provided bill credits to our customers in 2013 and 2014. For the years ended December 31, 2014 and December 31, 2013, $17.4 million and $48.0 million, respectively, was recognized as income, which reflects the amount that was returned to customers in the form of bill credits during the year. The accounting reflects the regulatory treatment of the grant.
In June 2014, we received approximately $76.2 million related to the Treasury Grant. The PSCW approved escrow accounting for the Treasury Grant and the proceeds we received that exceeded the amounts originally included in rates are being returned to customers in the form of bill credits.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2014
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS
	Revenue Recognition:   In May 2014, the Financial Accounting Standards Board and the International Accounting Standards Board issued their joint revenue recognition standard, Accounting Standards Update 2014-09, Revenue from Contracts with Customers. This guidance is effective for fiscal years and interim periods beginning after December 15, 2016, and 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.

Regulatory_Assets_and_Liabilit

Regulatory Assets and Liabilities	12 Months Ended
	Dec. 31, 2014
Regulatory Assets and Liabilities Disclosure [Abstract]
REGULATORY ASSETS AND LIABILITIES	REGULATORY ASSETS AND LIABILITIES
	Our primary regulator, the PSCW, considers our regulatory assets and liabilities in two categories, escrowed and deferred. In escrow accounting we expense amounts that are included in rates. If actual costs exceed or are less than the amounts that are allowed in rates, the difference in cost is escrowed on the balance sheet as a regulatory asset or regulatory liability and the escrowed balance is considered in setting future rates. Under deferred cost accounting, we defer amounts to our balance sheet based upon orders or correspondence with our regulators. These deferred costs will be considered in future rate setting proceedings. As of December 31, 2014, we had $12.8 million of regulatory assets not earning a return and $115.1 million of regulatory assets earning a return based on short-term interest rates.
	In December 2014, the PSCW issued a rate order effective January 1, 2015 that, among other things, reaffirmed our accounting for the regulatory assets and liabilities identified below.
	Our regulatory assets and liabilities as of December 31 consist of:
		2014		2013
		(Millions of Dollars)
	Regulatory Assets
	Deferred unrecognized pension costs	$	629.5	$	537.6
	Deferred income tax related	176		169.5
	Escrowed electric transmission costs	146		126.8
	Escrowed PTF	66.6		49.3
	Escrowed conservation	58		66.9
	Deferred plant related -- capital lease	42.3		56.5
	Deferred environmental costs	45.9		47
	Other, net	106.9		54.9
	Total regulatory assets	$	1,271.20	$	1,108.50
	Regulatory Liabilities
	Deferred cost of removal obligations	$	741.1	$	724.5
	Escrowed bad debt costs	30.1		64.6
	Other, net	59.4		90
	Total regulatory liabilities	$	830.6	$	879.1

Acquisition_Acquisition_Note

Acquisition Acquisition (Note)	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	ACQUISITION
	On June 22, 2014, Wisconsin Energy and Integrys entered into an agreement and plan of merger (Merger Agreement) under which Wisconsin Energy will acquire Integrys. Integrys’ shareholders will receive 1.128 shares of Wisconsin Energy common stock and $18.58 in cash per Integrys share of common stock. We expect to finance the acquisition through the issuance of approximately 91 million shares of Wisconsin Energy common stock to Integrys shareholders and through the issuance of approximately $1.5 billion of debt. We will also assume all of Integrys' outstanding debt. The combined company will be named WEC Energy Group, Inc.
	The acquisition is subject to several conditions, including, among others, approval of the shareholders of both Wisconsin Energy and Integrys, the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR Act), and the receipt of approvals from various government agencies, including FERC, Federal Communications Commission, PSCW, Illinois Commerce Commission, MPSC and Minnesota Public Utilities Commission. The status of these matters as of December 31, 2014 is as follows:
	•	On August 6, 2014, we filed applications for approval with the PSCW, Illinois Commerce Commission, MPSC and Minnesota Public Utilities Commission.
	•	On August 15, 2014, we filed an application with the FERC. The initial public comment period closed on October 17, 2014. We subsequently submitted additional information to respond to FERC questions on December 18, 2014. That comment period is now closed.
	•	On September 24, 2014, we submitted our HSR Act filings, and on October 24, 2014, the United States Department of Justice closed its review of the transaction with no further action required. In addition, on October 24, 2014, the Federal Trade Commission granted early termination of the 30-day waiting period required by the HSR Act.
	•	On November 21, 2014, the shareholders of Wisconsin Energy voted to approve the issuance of common stock as contemplated by the Merger Agreement, as well as to amend the restated articles of incorporation to change the name of Wisconsin Energy from Wisconsin Energy Corporation to WEC Energy Group, Inc. The shareholders of Integrys approved the adoption of the Merger Agreement at its shareholder meeting held on November 21, 2014.
	We anticipate the transaction closing in the second half of 2015.

Asset_Retirement_Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
ASSET RETIREMENT OBLIGATIONS	ASSET RETIREMENT OBLIGATIONS
	AROs have been recorded for asbestos abatement at certain generation and substation facilities, and for obligations associated with the removal and dismantlement of generation facilities. AROs are recorded in other long-term liabilities on the Consolidated Balance Sheets. The following table presents the change in our AROs during 2014 and 2013:
		2014			2013
		(Millions of Dollars)
	Balance as of January 1	$	42.3		$	44.3
	Liabilities Settled	(1.1		)	(4.4		)
	Accretion	2.4			2.4
	Balance as of December 31	$	43.6		$	42.3

Variable_Interest_Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2014
Variable Interest Entities [Abstract]
VARIABLE INTEREST ENTITIES	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 eight 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 $174.0 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 in 2014, 2013 and 2012 were $53.0 million, $50.3 million and $45.8 million, respectively. Our maximum exposure to loss is limited to the capacity payments under the contract.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES
	The following table is a summary of income tax expense for each of the years ended December 31:
	Income Taxes		2014				2013				2012
			(Millions of Dollars)
	Current tax expense		$	33.6			$	25.2			$	13.1
	Deferred income taxes, net		329.2				313.8				294.4
	Investment tax credit, net		(1.1		)		(1.1		)		(1.2		)
	Total Income Tax Expense		$	361.7			$	337.9			$	306.3
	The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to income before income taxes as a result of the following:
			2014							2013						2012
							Effective							Effective					Effective
	Income Tax Expense		Amount				Tax Rate			Amount				Tax Rate		Amount			Tax Rate
			(Millions of Dollars)
	Expected tax at statutory federal tax rates		$	332.5			35	%		$	320.3			35	%	$	298.4		35	%
	State income taxes net of federal tax benefit		50.5				5.3	%		49				5.3	%	43.3			5.1	%
	Production tax credits		(17.4		)		(1.8	)%		(16.7		)		(1.8	)%	(15.9		)	(1.9	)%
	Treasury Grant		(3.8		)		(0.4	)%		(7.4		)		(0.8	)%	—			—	%
	AFUDC - Equity		(1.9		)		(0.2	)%		(6.4		)		(0.7	)%	(12.3		)	(1.4	)%
	Investment tax credit restored		(1.1		)		(0.1	)%		(1.1		)		(0.1	)%	(1.2		)	(0.1	)%
	Domestic production activities deduction		—				—	%		—				—	%	(12.6		)	(1.5	)%
	Other, net		2.9				0.3	%		0.2				—	%	6.6			0.7	%
	Total Income Tax Expense		$	361.7			38.1	%		$	337.9			36.9	%	$	306.3		35.9	%
	The components of deferred income taxes classified as net current assets and net long-term liabilities as of December 31 are as follows:
	Deferred Tax Assets		2014				2013
			(Millions of Dollars)
	Current
	Future federal tax benefits		$	221.7			$	309.7
	Employee benefits and compensation		13.7				13.8
	Other		47.7				56
	Total Current Deferred Tax Assets		283.1				379.5
	Non-current
	Deferred revenues		221.3				237
	Employee benefits and compensation		98.2				95.6
	Future federal tax benefits		—				32.5
	Property-related		28.8				28.2
	Construction advances		18.9				18.3
	Other		51.8				62.9
	Total Non-Current Deferred Tax Assets		419				474.5
	Total Deferred Tax Assets		$	702.1			$	854
	Deferred Tax Liabilities		2014				2013
			(Millions of Dollars)
	Current
	Prepaid items		$	40.4			$	69.5
	Total Current Deferred Tax Liabilities		40.4				69.5
	Non-current
	Property-related		2,750.40				2,574.40
	Employee benefits and compensation		242.5				238.5
	Investment in transmission affiliate		188.6				169.9
	Deferred transmission costs		58.5				50.8
	Other		85.7				74.9
	Total Non-current Deferred Tax Liabilities		3,325.70				3,108.50
	Total Deferred Tax Liabilities		$	3,366.10			$	3,178.00
	Consolidated Balance Sheet Presentation		2014				2013
	Current Deferred Tax Asset		$	242.7			$	310
	Non-Current Deferred Tax Liability		$	2,906.70			$	2,634.00
	Consistent with rate-making treatment, deferred taxes are offset in the above table for temporary differences which have related regulatory assets or liabilities.
	As of December 31, 2014, we had approximately $416.2 million and $76.0 million of net operating loss and tax credit carryforwards resulting in deferred tax assets of $145.7 million and $76.0 million, respectively. As of December 31, 2013, we had approximately $810.3 million and $58.6 million of net operating loss and tax credit carryforwards resulting in deferred tax assets of $283.6 million and $58.6 million, respectively. The tax credit and net operating loss carryforwards begin to expire in 2029. We anticipate that we will have future taxable income sufficient to utilize these deferred tax assets.
	We previously adopted accounting guidance related to uncertainty in income taxes. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:
		2014				2013
		(Millions of Dollars)
	Balance as of January 1	$	8.4			$	11.3
	Reductions for tax positions of prior years	(1.2		)		(2.9		)
	Balance as of December 31	$	7.2			$	8.4
	The amount of unrecognized tax benefits as of December 31, 2014 and 2013 excludes deferred tax assets related to uncertainty in income taxes of $7.2 million and $8.4 million, respectively. As of December 31, 2014 and 2013, there were no unrecognized tax benefits that, if recognized, would impact the effective tax rate for continuing operations.
We recognize interest and penalties accrued related to unrecognized tax benefits as a component of income tax expense. For the years ended December 31, 2014, 2013 and 2012, we recognized approximately $0.3 million, $0.2 million and $0.2 million, respectively, of accrued interest in the Consolidated Income Statements. For the years ended December 31, 2014, 2013 and 2012, we recognized no penalties in the Consolidated Income Statements. We had approximately $0.7 million and $0.4 million of interest accrued and no penalties accrued on the Consolidated Balance Sheets as of December 31, 2014 and 2013, respectively.
We do not anticipate any significant increases or decreases in the total amounts of unrecognized tax benefits within the next 12 months.
Our primary tax jurisdictions include the United States and the state of Wisconsin. Currently, the tax years of 2011 through 2014 are subject to Federal examination, and the tax years 2010 through 2014 are subject to examination by the state of Wisconsin.

Common_Equity

Common Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
COMMON EQUITY	COMMON EQUITY
	As of December 31, 2014 and 2013, we had 325,000,000 shares of common stock, one cent par value, authorized under our charter, of which 225,517,339 and 225,962,959 common shares, respectively, were outstanding. All share-based compensation is currently fulfilled by purchases on the open market by our independent agents and do not dilute shareholders' ownership.
	Acquisition of Integrys: On June 22, 2014, we entered into an agreement to acquire Integrys. Integrys shareholders will receive 1.128 shares of Wisconsin Energy common stock and $18.58 in cash per share of Integrys common stock. The proposed acquisition is scheduled to close in the second half of 2015. We expect to finance the acquisition through the issuance of approximately $1.5 billion of debt and approximately 91 million shares of Wisconsin Energy common stock.
	Share-Based Compensation Plans:   We have a plan that was approved by stockholders that enables us to provide a long-term incentive through equity interests in Wisconsin Energy to outside directors, selected officers and key employees of the Company. The plan provides for the granting of stock options, stock appreciation rights, restricted stock awards and performance shares. Awards may be paid in common stock, cash or a combination thereof. We utilize the straight-line attribution method for recognizing share-based compensation expense. Accordingly, for employee awards, equity classified share-based compensation cost is measured at the grant date based on the fair value of the award, and is recognized as expense over the requisite service period. There were no modifications to the terms of outstanding stock options during the period.
	The following table summarizes recorded pre-tax share-based compensation expense and the related tax benefit for share-based awards made to our employees and directors as of December 31:
		2014				2013			2012
		(Millions of Dollars)
	Performance units	$	15.4			$	12.7		$	16.3
	Stock options	3.7				3.9			2.7
	Restricted stock	2.8				2.4			3
	Share-based compensation expense	$	21.9			$	19		$	22
	Related Tax Benefit	$	8.8			$	7.6		$	8.8
	Stock Options:   The exercise price of a stock option under the plan is to be no less than 100% of the common stock's fair market value on the grant date and options may not be exercised within six months of the grant date except in the event of a change in control. Option grants consist of non-qualified stock options that vest on a cliff-basis after a three year period. Options expire no later than 10 years from the date of grant. For further information regarding stock-based compensation and the valuation of our stock options, see Note A.
	We expect that substantially all of the outstanding options as of December 31, 2014 will be exercised.
	The following is a summary of our stock option activity during 2014:
	Stock Options		Number of Options			Weighted-Average Exercise Price			Weighted-Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value (Millions)
	Outstanding as of January 1, 2014		8,089,710			$	26.84
	Granted		899,500			$	41.03
	Exercised		(2,201,821	)		$	22.85
	Forfeited		(17,195	)		$	37.42
	Outstanding as of December 31, 2014		6,770,194			$	29.99		5.7		$	154
	Exercisable as of December 31, 2014		3,890,339			$	24.1		3.9		$	111.4
	In January 2015, the Compensation Committee of the Board of Directors (Compensation Committee) awarded 516,475 non-qualified stock options with an exercise price of $52.895 to our officers and other key employees under its normal schedule of awarding long-term incentive compensation.
	The intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $50.5 million, $44.5 million and $47.5 million, respectively. Cash received from options exercised during the years ended December 31, 2014, 2013 and 2012 was $50.3 million, $48.5 million and $49.8 million, respectively. The actual tax benefit realized for the tax deductions from option exercises for the same periods was approximately $19.9 million, $17.8 million and zero, respectively.
	The following table summarizes information about stock options outstanding as of December 31, 2014:
			Options Outstanding								Options Exercisable
						Weighted-Average							Weighted-Average
	Range of Exercise Prices		Number of Options			Exercise Price			Remaining Contractual Life (Years)		Number of Options		Exercise Price		Remaining Contractual Life (Years)
	$17.10  to  $21.11		1,498,071			$	20.86		3.5		1,498,071		$	20.86	3.5
	$23.88  to  $29.35		2,153,513			$	25.06		3.7		2,153,513		$	25.06	3.7
	$34.88  to  $41.03		3,118,610			$	37.79		8		238,755		$	35.88	7.4
			6,770,194			$	29.99		5.7		3,890,339		$	24.1	3.9
	The following table summarizes information about our non-vested options during 2014:
	Non-Vested Stock Options		Number of Options			Weighted- Average Fair Value
	Non-Vested as of January 1, 2014		2,380,790			$	3.38
	Granted		899,500			$	4.18
	Vested		(383,240	)		$	3.26
	Forfeited		(17,195	)		$	3.56
	Non-Vested as of December 31, 2014		2,879,855			$	3.65
	As of December 31, 2014, total compensation costs related to non-vested stock options not yet recognized was approximately $2.1 million, which is expected to be recognized over the next 19 months on a weighted-average basis.
	Restricted Shares:   The Compensation Committee has also approved restricted stock grants to certain key employees and directors. The following restricted stock activity occurred during 2014:
	Restricted Shares		Number of Shares			Weighted-Average Market Price
	Outstanding as of January 1, 2014		150,698
	Granted		71,504			$	40.96
	Released		(63,509	)		$	33.02
	Forfeited		(3,214	)		$	38.47
	Outstanding as of December 31, 2014		155,479
	In January 2015, the Compensation Committee awarded 60,164 restricted shares to our directors, officers and other key employees under its normal schedule of awarding long-term incentive compensation. These awards have a three-year vesting period, and generally, one-third of the award vests on each anniversary of the grant date. During the vesting period, restricted share recipients also have voting rights and are entitled to dividends in the same manner as other shareholders.
	We record the market value of the restricted stock awards on the date of grant and then we charge their value to expense over the vesting period of the awards. The intrinsic value of restricted stock vesting was $2.7 million, $4.0 million and $3.5 million for the years ended December 31, 2014, 2013, and 2012, respectively. The actual tax benefit realized for the tax deductions from released restricted shares for the same years was $1.0 million, $1.3 million and zero, respectively.
	As of December 31, 2014, total compensation cost related to restricted stock not yet recognized was approximately $2.8 million, which is expected to be recognized over the next 20 months on a weighted-average basis.
	Performance Units:   In January 2014, 2013 and 2012, the Compensation Committee awarded 233,735, 239,120 and 346,570 performance units, respectively, to officers and other key employees under the Wisconsin Energy Performance Unit Plan. Under the grants, the ultimate number of units that will be awarded is dependent upon the achievement of certain financial performance of our stock over a three-year period. Under the terms of the award, participants may earn between 0% and 175% of the base performance unit award. All grants are settled in cash. We are accruing compensation costs over the three-year performance period based on our estimate of the final expected value of the awards. Performance units earned as of December 31, 2014, 2013 and 2012 vested and were settled during the first quarter of 2015, 2014 and 2013, and had a total intrinsic value of $13.2 million, $14.8 million and $19.3 million, respectively. The actual tax benefit realized for the tax deductions from the distribution of performance units was approximately $4.8 million, $5.3 million and $7.0 million, respectively.
	In January 2015, the Compensation Committee awarded 195,365 performance units to our officers and other key employees under its normal schedule of awarding long-term incentive compensation.
	As of December 31, 2014, total compensation cost related to performance units not yet recognized was approximately $12.6 million, which is expected to be recognized over the next 20 months on a weighted-average basis.
	Restrictions:   Wisconsin Energy's ability as a holding company to pay common dividends primarily depends on the availability of funds received from its non-utility subsidiary, We Power, and its utility subsidiaries.
	Various financing arrangements and regulatory requirements impose certain restrictions on the ability of our subsidiaries to transfer funds to Wisconsin Energy in the form of cash dividends, loans or advances. In addition, under Wisconsin law, Wisconsin Electric and Wisconsin Gas are prohibited from loaning funds, either directly or indirectly, to Wisconsin Energy.
	Wisconsin Electric and Wisconsin Gas are required to maintain capital structures that differ from GAAP as they reflect regulatory adjustments. The 2013 PSCW rate case order required Wisconsin Electric to maintain a common equity ratio range of between 48.5% and 53.5%, and Wisconsin Gas to maintain a capital structure which had a common equity range of between 45.0% and 50.0%. The 2015 PSCW rate case requires Wisconsin Electric to maintain a common equity ratio range of between 48.5% and 53.5%, and Wisconsin Gas to maintain a capital structure which has a common equity range of between 47.0% and 52.0%. Each company is in compliance with its respective common equity range as outlined within the 2013 PSCW rate case. Wisconsin Electric and Wisconsin Gas must obtain PSCW approval if they pay dividends above the test year levels that would cause either company to fall below the authorized levels of common equity.
	Wisconsin Electric may not pay common dividends to Wisconsin Energy under Wisconsin Electric's Restated Articles of Incorporation if any dividends on Wisconsin Electric's outstanding preferred stock have not been paid. In addition, pursuant to the terms of Wisconsin Electric's 3.60% Serial Preferred Stock, Wisconsin Electric's ability to declare common dividends would be limited to 75% or 50% of net income during a twelve month period if Wisconsin Electric's common stock equity to total capitalization, as defined in the preferred stock designation, is less than 25% and 20%, respectively.
	We have the option to defer interest payments on the Junior Notes, from time to time, for one or more periods of up to 10 consecutive years per period. During any period in which we defer interest payments, we may not declare or pay any dividends or distributions on, or redeem, repurchase or acquire, our common stock.
	As of December 31, 2014, the restricted net assets of consolidated and unconsolidated subsidiaries and our equity in undistributed earnings of 50% or less owned investees accounted for by the equity method total approximately $3.7 billion. This amount exceeds 25% of our consolidated net assets as of December 31, 2014.
	See Note K for discussion of certain financial covenants related to the bank back-up credit facilities of Wisconsin Energy, Wisconsin Electric and Wisconsin Gas.
	We do not believe that these restrictions will materially affect our operations or limit any dividend payments in the foreseeable future.
	Share Repurchase Program:   We do not expect to issue new shares under our various employee benefit plans and our dividend reinvestment and share purchase plan; rather, we instruct independent plan agents to purchase the shares in the open market. In that regard, no new shares of common stock were issued in 2014, 2013 or 2012.
	In December 2013, our Board of Directors authorized a share repurchase program for the purchase of up to $300.0 million of our common stock through open market purchases or privately negotiated transactions from January 1, 2014 through the end of 2017. On June 22, 2014, in connection with the proposed acquisition of Integrys, the Board of Directors terminated this share repurchase program. For the twelve months ended December 31, 2014, we repurchased $18.6 million of our common stock pursuant to the terminated program at an average cost of $43.66 per share. All of these shares were purchased during the first quarter of 2014. A previous share repurchase program authorized by our Board of Directors expired at the end of 2013. In addition, we have instructed our independent agents to purchase shares on the open market to fulfill exercised stock options and restricted stock awards. The following table identifies the shares purchased by the Company for the year ending December 31:
		2014						2013						2012
	Shares			Cost			Shares			Cost			Shares	Cost
	(In Millions)
Under share repurchase programs	0.4			$	18.6		3			$	126		1.5	$	51.8
To fulfill exercised stock options and restricted stock awards	2.3			104.6			2.4			97.4			2.8	101.4
Total	2.7			$	123.2		5.4			$	223.4		4.3	$	153.2

Preferred_Stock_Notes

Preferred Stock (Notes)	12 Months Ended
	Dec. 31, 2014
Preferred Stock [Abstract]
Preferred Stock [Text Block]	PREFERRED STOCK
	The following table shows preferred stock authorized and outstanding at December 31, 2014 and 2013:
		Shares Authorized	Shares Outstanding	Redemption Price Per Share		Total
						(In Millions)
	Wisconsin Energy
	$.01 par value Preferred Stock	15,000,000	—	—		$	—
	Wisconsin Electric
	$100 par value, Six Per Cent. Preferred Stock	45,000	44,498	—		$	4.4
	$100 par value, Serial Preferred Stock	2,286,500
	3.60% Series		260,000	$	101	26
	$25 par value, Serial Preferred Stock	5,000,000	—	—		—
	Total preferred stock of subsidiary					$	30.4

LongTerm_Debt_and_Capital_Leas

Long-Term Debt and Capital Lease Obligations	12 Months Ended
	Dec. 31, 2014
Long-term Debt and Capital Lease Obligations [Abstract]
LONG-TERM DEBT AND CAPITAL LEASE OBLIGATIONS	LONG-TERM DEBT AND CAPITAL LEASE OBLIGATIONS
	Debentures and Notes:   As of December 31, 2014, the maturities and sinking fund requirements of our long-term debt outstanding (excluding obligations under capital leases) were as follows:
		(Millions of Dollars)
	2015	$	399.5
	2016	27.4
	2017	29.5
	2018	281.1
	2019	282.7
	Thereafter	3,532.20
	Total	$	4,552.40
	We amortize debt premiums, discounts and debt issuance costs over the lives of the debt and we include the costs in interest expense.
	Wisconsin Electric is the obligor under two series of tax-exempt pollution control refunding bonds in outstanding principal amount of $147 million. In August 2009, Wisconsin Electric terminated letters of credit that provided credit and liquidity support for the bonds, which resulted in a mandatory tender of the bonds. Wisconsin Electric purchased the bonds at par plus accrued interest to the date of purchase. As of December 31, 2014 and 2013, the repurchased bonds were still outstanding, but were not reported in our consolidated long-term debt or included on our Consolidated Statements of Capitalization because they are held by Wisconsin Electric. Depending on market conditions and other factors, Wisconsin Electric may change the method used to determine the interest rate on the bonds and have them remarketed to third parties.
	In connection with our outstanding Junior Notes, we executed the Replacement Capital Covenant dated May 11, 2007 (RCC) for the benefit of persons that buy, hold or sell a specified series of long-term indebtedness (covered debt). Our 6.20% Senior Notes due April 1, 2033 have been designated as the covered debt under the RCC. The RCC provides that we may not redeem, defease or purchase and our subsidiaries may not purchase any Junior Notes on or before May 15, 2037, unless, subject to certain limitations described in the RCC, during the 180 days prior to the date of redemption, defeasance or purchase, we have received a specified amount of proceeds from the sale of qualifying securities.
	Effective May 2017, the $500 million of Junior Notes will bear interest at the three-month LIBOR Rate plus 211.25 basis points and will reset quarterly.
	Obligations Under Capital Leases:   In 1997, Wisconsin Electric entered into a 25-year power purchase contract with an unaffiliated independent power producer. The contract, for 236 MW of firm capacity from a gas-fired cogeneration facility, includes no minimum energy requirements. When the contract expires in 2022, Wisconsin Electric may, at its option and with proper notice, renew for another ten years or purchase the generating facility at fair value or allow the contract to expire. We account for this contract as a capital lease and recorded the leased facility and corresponding obligation under the capital lease at the estimated fair value of the plant's electric generating facilities. We are amortizing the leased facility on a straight-line basis over the original 25-year term of the contract.
	We treat the long-term power purchase contract as an operating lease for rate-making purposes and we record our minimum lease payments as purchased power expense on the Consolidated Income Statements. We paid a total of $34.9 million and $33.7 million in lease payments during 2014 and 2013, respectively. We record the difference between the minimum lease payments and the sum of imputed interest and amortization costs calculated under capital lease accounting as a deferred regulatory asset on our Consolidated Balance Sheets (see Regulatory Assets - Deferred plant related -- capital lease in Note C). Due to the timing and the amounts of the minimum lease payments, the regulatory asset increased to approximately $78.5 million during 2009, at which time the regulatory asset began to be reduced to zero over the remaining life of the contract. The total obligation under the capital lease was $84.5 million as of December 31, 2014, and will decrease to zero over the remaining life of the contract.
	The following is a summary of our capitalized leased facilities as of December 31:
	Capital Lease Assets		2014			2013
			(Millions of Dollars)
	Leased Facilities
	Long-term power purchase commitment		$	140.3		$	140.3
	Accumulated amortization		(98.3		)	(92.5		)
	Total Leased Facilities		$	42		$	47.8
	Future minimum lease payments under our capital lease and the present value of our net minimum lease payments as of December 31, 2014 are as follows:
		(Millions of Dollars)
	2015	$	43.5
	2016	45.1
	2017	13.9
	2018	14.7
	2019	15.5
	Thereafter	41.3
	Total Minimum Lease Payments	174
	Less:  Estimated Executory Costs	(54.7		)
	Net Minimum Lease Payments	119.3
	Less:  Interest	(34.8		)
	Present Value of Net
	Minimum Lease Payments	84.5
	Less:  Due Currently	(24.6		)
		$	59.9

ShortTerm_Debt

Short-Term Debt	12 Months Ended
	Dec. 31, 2014
Short-term Debt [Abstract]
SHORT-TERM DEBT	SHORT-TERM DEBT
	Short-term notes payable balances and their corresponding weighted-average interest rates as of December 31 consist of:
			2014					2013
						Interest				Interest
	Short-Term Debt		Balance			Rate		Balance		Rate
			(Millions of Dollars, except for percentages)
	Commercial paper		$	617.6		0.22	%	$	537.4	0.2	%
	The following information relates to commercial paper for the years ended December 31:
		2014			2013
		(Millions of Dollars, except for percentages)
	Maximum Short-Term Debt Outstanding	$	721.4		$	594.5
	Average Short-Term Debt Outstanding	$	468.1		$	359.1
	Weighted-Average Interest Rate	0.18		%	0.25		%
	Wisconsin Energy, Wisconsin Electric and Wisconsin Gas have entered into bank back-up credit facilities to maintain short-term credit liquidity which, among other terms, require the companies to maintain, subject to certain exclusions, a minimum total funded debt to capitalization ratio of less than 70%, 65% and 65%, respectively.
	As of December 31, 2014, we had approximately $1.2 billion of available undrawn lines under our bank back-up credit facilities and $617.6 million of commercial paper outstanding that was supported by the available lines of credit. In December 2014, we amended each of our credit facilities to extend their expirations from December 2017 to December 2019.
	The Wisconsin Energy, Wisconsin Electric and Wisconsin Gas bank back-up credit facilities contain customary covenants, including certain limitations on the respective companies' ability to sell assets. The credit facilities also contain customary events of default, including payment defaults, material inaccuracy of representations and warranties, covenant defaults, bankruptcy proceedings, certain judgments, Employee Retirement Income Security Act of 1974 (ERISA) defaults and change of control. In addition, pursuant to the terms of Wisconsin Energy's credit agreement, Wisconsin Energy must ensure that certain of its subsidiaries comply with several of the covenants contained therein.
	As of December 31, 2014, we were in compliance with all financial covenants.

Derivative_Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [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 and shareholders. 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 December 31, 2014, we recognized $14.7 million in regulatory assets and $14.2 million in regulatory liabilities related to derivatives in comparison to $0.3 million in regulatory assets and $9.6 million in regulatory liabilities as of December 31, 2013.
	We record our current derivative assets on the balance sheet in other current assets and the current portion of the liabilities in other current liabilities. The long-term portion of our derivative assets of $0.6 million is recorded in other deferred charges and other assets, and the long-term portion of our derivative liabilities of $0.8 million is recorded in other deferred credit and other liabilities. Our Consolidated Balance Sheets as of December 31, 2014 and 2013 include:
		December 31, 2014							December 31, 2013
		Derivative				Derivative			Derivative			Derivative
		Asset				Liability			Asset			Liability
		(Millions of Dollars)
	Natural Gas	$	5			$	12.3		$	5.6		$	0.1
	Fuel Oil	—				—			0.6			—
	FTRs	7				—			3.5			—
	Coal	3.3				0.2			2.1			0.2
	Total	$	15.3			$	12.5		$	11.8		$	0.3
	Our Consolidated 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) for the years ended December 31 were as follows:
		2014						2013
		Volume		Gains				Volume	Gains (Losses)
				(Millions of Dollars)					(Millions of Dollars)
	Natural Gas	40.5 million Dth		$	7.3			48.6 million Dth	$	(8.5	)
	Fuel Oil	9.2 million gallons		0.5				8.6 million gallons	0.5
	FTRs	26.1 million MWh		12.7				25.3 million MWh	14.9
	Total			$	20.5				$	6.9
	As of December 31, 2014 and 2013, we posted collateral of $11.2 million and zero, 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 December 31, 2014 and 2013.
		2014							2013
		Derivative				Derivative			Derivative			Derivative
		Asset				Liability			Asset			Liability
		(Millions of Dollars)
	Gross Amount Recognized on the Balance Sheet	$	15.3			$	12.5		$	11.8		$	0.3
	Gross Amount Not Offset on Balance Sheet (a)	(0.4		)		(11.5		)	—			—
	Net Amount	$	14.9			$	1		$	11.8		$	0.3
	(a)	Gross Amount Not Offset on Balance Sheet includes cash collateral posted of $10.3 million and zero as of December 31, 2014 and 2013, respectively.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [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 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 December 31, 2014
			Level 1			Level 2		Level 3		Total
			(Millions of Dollars)
	Assets:
	Derivatives		$	1.1		$	7.2	$	7	15.3
	Total		$	1.1		$	7.2	$	7	$	15.3
	Liabilities:
	Derivatives		$	11.5		$	1	$	—	$	12.5
	Total		$	11.5		$	1	$	—	$	12.5
	Recurring Fair Value Measures		As of December 31, 2013
			Level 1			Level 2		Level 3		Total
			(Millions of Dollars)
	Assets:
	Derivatives		$	5.7		$	2.6	$	3.5	$	11.8
	Total		$	5.7		$	2.6	$	3.5	$	11.8
	Liabilities:
	Derivatives		$	—		$	0.3	$	—	$	0.3
	Total		$	—		$	0.3	$	—	$	0.3
	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:
		2014			2013
		(Millions of Dollars)
	Balance as of January 1	$	3.5		$	4.7
	Realized and unrealized gains (losses)	—			—
	Purchases	15.6			10.6
	Issuances	—			—
	Settlements	(12.1		)	(11.8		)
	Transfers in and/or out of Level 3	—			—
	Balance as of December 31	$	7		$	3.5
	Derivative instruments reflected in Level 3 of the hierarchy include MISO 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 L -- 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 as of December 31 are as follows:
			2014					2013
			Carrying			Fair		Carrying		Fair
	Financial Instruments		Amount			Value		Amount		Value
			(Millions of Dollars)
	Preferred stock, no redemption required		$	30.4		$	27.1	$	30.4	$	26
	Long-term debt including current portion		$	4,552.40		$	5,126.00	$	4,626.70	$	4,911.80
	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.

Benefits

Benefits	12 Months Ended
	Dec. 31, 2014
General Discussion of Pension and Other Postretirement Benefits [Abstract]
BENEFITS	- BENEFITS
	Pensions and Other Post-retirement Benefits:   We have defined benefit pension plans that cover substantially all of our employees. Generally, employees who started with the Company after 1995 receive a benefit based on a percentage of their annual salary plus an interest credit, while employees who started before 1996 receive a benefit based upon years of service and final average salary. Approximately half of our projected benefit obligation relates to benefits based upon years of service and final average salary. New management employees hired after December 31, 2014 will receive a 6% annual Company contribution to their 401(k) plan instead of being enrolled in the defined benefit plans.
	We also have OPEB plans covering substantially all of our employees. The health care plans are contributory with participants' contributions adjusted annually; the life insurance plans are noncontributory. The accounting for the health care plans anticipates future cost-sharing changes to the written plans that are consistent with our expressed intent to maintain the current cost sharing levels. The post-retirement health care plans include a limit on our share of costs for recent and future retirees.
	We use a year-end measurement date to measure the funded status of all of our pension and OPEB plans. Due to the regulated nature of our business, we have concluded that substantially all of the unrecognized costs resulting from the recognition of the funded status of our pension and OPEB plans qualify as a regulatory asset.
	The following table presents details about our pension and OPEB plans:
		Pension							OPEB
		2014				2013			2014			2013
		(Millions of Dollars)
	Change in Benefit Obligation
	Benefit Obligation at January 1	$	1,410.20			$	1,508.50		$	362.7		$	381.2
	Service cost	10.1				14.6			8.5			10
	Interest cost	68.1				60.4			17.8			15.6
	Participants' contributions	—				—			9.1			8.9
	Plan amendments	—				(1.0		)	(4.6		)	—
	Actuarial loss (gain)	120.4				(81.9		)	29.4			(27.7		)
	Gross benefits paid	(103.3		)		(90.4		)	(26.4		)	(26.3		)
	Federal subsidy on benefits paid	N/A				N/A			1.2			1
	Benefit Obligation at December 31	$	1,505.50			$	1,410.20		$	397.7		$	362.7
	Change in Plan Assets
	Fair Value at January 1	$	1,451.00			$	1,385.40		$	327.6		$	285.4
	Actual earnings on plan assets	88.5				147.3			17.7			45.5
	Employer contributions	8.4				8.7			5.5			14.1
	Participants' contributions	—				—			9.1			8.9
	Gross benefits paid	(103.3		)		(90.4		)	(26.4		)	(26.3		)
	Fair Value at December 31	$	1,444.60			$	1,451.00		$	333.5		$	327.6
	Net liability (asset)	$	60.9			$	(40.8	)	$	64.2		$	35.1
	Amounts recognized in our Consolidated Balance Sheets as of December 31 related to the funded status of the benefit plans consisted of:
		Pension							OPEB
		2014				2013			2014			2013
		(Millions of Dollars)
	Other long-term assets	$	39.2			$	138.7		$	39.5		$	40.2
	Other long-term liabilities	100.1				97.9			103.7			75.3
	Net liability (asset)	$	60.9			$	(40.8	)	$	64.2		$	35.1
	The accumulated benefit obligation for all defined pension plans was $1,504.6 million and $1,409.5 million as of December 31, 2014, and 2013, respectively.
	The following table shows the amounts that have not yet been recognized in our net periodic benefit cost as of December 31 and are recorded as a regulatory asset on our balance sheet:
		Pension							OPEB
		2014				2013			2014			2013
		(Millions of Dollars)
	Net actuarial loss	$	622.7			$	528.8		$	44.1		$	9.8
	Prior service costs (credits)	6.8				8.8			(4.6		)	(1.7		)
	Total - Regulatory Assets	$	629.5			$	537.6		$	39.5		$	8.1
	We estimate that 2015 periodic pension and OPEB costs will include the amortization of previously unrecognized benefit costs referred to above of $48.3 million and $0.9 million, respectively.
	The components of net periodic pension and OPEB costs for the years ended December 31 are as follows:
		Pension										OPEB
		2014				2013			2012			2014			2013			2012
		(Millions of Dollars)
	Net Periodic Benefit Cost
	Service cost	$	10.1			$	14.6		$	21.7		$	8.5		$	10		$	10.3
	Interest cost	68.1				60.4			65.5			17.8			15.6			20.3
	Expected return on plan assets	(98.6		)		(95.8		)	(89.6		)	(23.7		)	(21.3		)	(19.0		)
	Amortization of:
	Transition obligation	—				—			—			—			—			0.3
	Prior service cost (credit)	2.1				2.3			2.2			(1.8		)	(2.0		)	(1.9		)
	Actuarial loss	36.7				54.5			41			1.2			3.7			7.3
	Settlement charge	—				2.5			—			—			—			—
	Other	—				—			0.4			—			—			—
	Net Periodic Benefit Cost	$	18.4			$	38.5		$	41.2		$	2		$	6		$	17.3
		Pension						OPEB
		2014		2013		2012		2014	2013		2012
	Weighted-Average assumptions used to
	determine benefit obligations as of Dec. 31
	Discount rate	4.15%		5.00%		4.10%		4.20%	4.95%		4.15%
	Rate of compensation increase	4.00%		4.00%		4.00%		N/A	N/A		N/A
	Weighted-Average assumptions used to
determine net cost for year ended Dec. 31
Discount rate	5.00%		4.10%		5.05%		4.95%	4.15%		5.20%
Expected return on plan assets	7.25%		7.25%		7.25%		7.50%	7.50%		7.50%
Rate of compensation increase	4.00%		4.00%		4.00%		N/A	N/A		N/A
Assumed health care cost trend rates as of Dec. 31		2014		2013		2012
Health care cost trend rate assumed for next year (Pre 65 / Post 65)		7.5%/7.5%		7.5%/7.5%		7.5%/7.5%
Rate that the cost trend rate gradually adjusts to		5.00%		5.00%		5.00%
Year that the rate reaches the rate it is assumed to remain at (Pre 65 / Post 65)		2021/2021		2021/2021		2017/2017
The expected long-term rate of return on pension and OPEB plan assets was 7.25% and 7.50%, respectively, in 2014, 2013 and 2012. We consult with our investment advisors on an annual basis to help us forecast expected long-term returns on plan assets by reviewing historical returns as well as calculating expected total trust returns using the weighted-average of long-term market returns for each of the major target asset categories utilized in the fund.
A one-percentage-point change in assumed health care cost trend rates would have the following effects:
	1% Increase				1% Decrease
	(Millions of Dollars)
Effect on
Post-retirement benefit obligation	$	30.2			$	(25.4	)
Total of service and interest cost components	$	3.1			$	(2.5	)
We use various Employees' Benefit Trusts to fund a major portion of OPEB. The majority of the trusts' assets are mutual funds.
Plan Assets:   Current pension trust assets and amounts which are expected to be contributed to the trusts in the future are expected to be adequate to meet pension payment obligations to current and future retirees.
The Investment Trust Policy Committee oversees investment matters related to all of our funded benefit plans. The Committee works with external actuaries and investment consultants on an on-going basis to establish and monitor investment strategies and target asset allocations. Forecasted cash flows for plan liabilities are regularly updated based on annual valuation results. Target allocations are determined utilizing projected benefit payment cash flows and risk analyses of appropriate investments. They are intended to reduce risk, provide long-term financial stability for the plans and maintain funded levels which meet long-term plan obligations while preserving sufficient liquidity for near-term benefit payments.
Previously, our pension plan target allocation was 45% equity investments and 55% fixed income investments. In late 2014, we began transitioning to a target asset allocation of 35% equity investments, 55% fixed income investments and 10% private equity and real estate investments. The current OPEB target asset allocation is 60% equity investments and 40% fixed income investments. Equity securities include investments in large-cap, mid-cap and small-cap companies primarily located in the United States. Fixed income securities include corporate bonds of companies from diversified industries, mortgage and other asset backed securities, commercial paper, and U.S. Treasuries.
The following table summarizes the fair value of our pension plan assets by asset category within the fair value hierarchy (for further level information, see Note M):
		As of December 31, 2014
Asset Category - Pension		Level 1				Level 2			Level 3			Total
		(Millions of Dollars)
Cash and Cash Equivalents		$	6.4			$	—		$	—		$	6.4
Equities:
U.S. Equity		503.8				—			—			503.8
International Equity		128.6				29.8			—			158.4
Fixed Income
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds		42.5				599.3			—			641.8
International Bonds		79.3				43.3			—			122.6
Private Equity and Real Estate		—				—			11.6			11.6
Total		$	760.6			$	672.4		$	11.6		$	1,444.60
		As of December 31, 2013
Asset Category - Pension		Level 1				Level 2			Level 3			Total
		(Millions of Dollars)
Cash and Cash Equivalents		$	21			$	—		$	—		$	21
Equities:
U.S. Equity		519.5				—			—			519.5
International Equity		146.2				35.7			—			181.9
Fixed Income
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds		108.4				505.2			—			613.6
International Bonds		78.1				36.9			—			115
Total		$	873.2			$	577.8		$	—		$	1,451.00
(a)	This category represents investment grade bonds of U.S. and foreign issuers denominated in U.S. dollars from diverse industries.
The following table summarizes the fair value of our OPEB plan assets by asset category within the fair value hierarchy:
		As of December 31, 2014
Asset Category - OPEB		Level 1				Level 2			Level 3			Total
		(Millions of Dollars)
Cash and Cash Equivalents		$	1.4			$	—		$	—		$	1.4
Equities:
U.S. Equity		146				—			—			146
International Equity		42.2				2.5			—			44.7
Fixed Income:
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds		3.5				112.4			—			115.9
International Bonds		17.5				7			—			24.5
Private Equity and Real Estate		—				—			1			1
Total		$	210.6			$	121.9		$	1		$	333.5
		As of December 31, 2013
Asset Category - OPEB		Level 1				Level 2			Level 3			Total
		(Millions of Dollars)
Cash and Cash Equivalents		$	2.6			$	—		$	—		$	2.6
Equities:
U.S. Equity		148				—			—			148
International Equity		46.9				2.8			—			49.7
Fixed Income:
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds		8.4				96.3			—			104.7
International Bonds		16.8				5.8			—			22.6
Total		$	222.7			$	104.9		$	—		$	327.6
(a)	This category represents investment grade bonds of U.S. and foreign issuers denominated in U.S. dollars from diverse industries.
In December 2014, our pension and OPEB plans began investing in private equity funds which are a Level 3 investment.
Cash Flows:
Historical employer contributions:
		Pension
Year		Qualified				Non-Qualified			OPEB
		(Millions of Dollars)
2012		$	95.6			$	7.1		$	17.7
2013		$	—			$	8.7		$	14.1
2014		$	—			$	8.4		$	5.5
In January 2015, we contributed $100.0 million to the qualified pension plan. Future contributions to the plans will be dependent upon many factors, including the performance of plan assets, long-term discount rates and mortality rates.
Estimated benefit payments:
Year		Pension				Gross OPEB
		(Millions of Dollars)
2015		$	104.7			$	25.5
2016		$	103.6			$	22.3
2017		$	104.3			$	22.8
2018		$	102.3			$	23.3
2019		$	102.4			$	24.1
2020-2024		$	491.8			$	122.5
Savings Plans:   We sponsor savings plans which allow employees to contribute a portion of their pre-tax and/or after-tax income in accordance with plan-specified guidelines. Under these plans, we expensed matching contributions of $14.2 million, $14.2 million and $13.8 million during 2014, 2013 and 2012, respectively.
Postemployment Benefits:   Postemployment benefits provided to former or inactive employees are recognized when an event occurs. The estimated liability for such benefits was $3.3 million and $4.2 million as of December 31, 2014 and 2013, respectively.

Segment_Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
SEGMENT REPORTING	SEGMENT REPORTING
	Our reportable segments as of December 31, 2014 include a utility energy segment and a non-utility energy segment. We have organized our reportable segments based upon the regulatory environment in which our utility subsidiaries operate and on how management makes decisions and measures performance. The segments are managed separately because each business requires different technology and marketing strategies. The accounting policies of the reportable operating segments are the same as those described in Note A.
	Our utility energy segment primarily includes our electric and natural gas utility operations. Our electric utility operation engages in the generation, distribution and sale of electric energy in southeastern (including metropolitan Milwaukee), east central and northern Wisconsin and in the Upper Peninsula of Michigan. Our natural gas utility operation is engaged in the purchase, distribution and sale of natural gas to retail customers and the transportation of customer-owned natural gas throughout Wisconsin. Our non-utility energy segment derives its revenues primarily from the ownership of electric power generating facilities for long-term lease to Wisconsin Electric.
	Summarized financial information concerning our reportable segments for each of the three years ended December 31, 2014 is shown in the following table.
			Reportable Segments							Eliminations
			Energy				Corporate &			& Reconciling			Total
	Year Ended		Utility		Non-Utility		Other (a)			Items			Consolidated
			(Millions of Dollars)
	December 31, 2014
	Operating Revenues (b)		$	4,941.30	$	447.1	$	1.3		$	(392.6	)	$	4,997.10
	Depreciation and Amortization		$	340.6	$	67.5	$	0.7		$	—		$	408.8
	Operating Income (Loss)		$	770.2	$	368.2	$	(26.3	)	$	—		$	1,112.10
	Equity in Earnings of Unconsolidated Affiliates		$	66	$	—	$	(0.1	)	$	—		$	65.9
	Interest Expense, Net		$	128.8	$	64.6	$	48.8		$	(0.7	)	$	241.5
	Income Tax Expense (Benefit)		$	268.9	$	121.4	$	(28.6	)	$	—		$	361.7
	Net Income (Loss)		$	447.2	$	182.8	$	588		$	(629.7	)	$	588.3
	Capital Expenditures		$	689.9	$	41.1	$	5.1		$	—		$	736.1
	Total Assets (c)		$	14,912.80	$	2,821.80	$	4,880.30		$	(7,451.5	)	$	15,163.40
	December 31, 2013
	Operating Revenues (b)		$	4,462.00	$	446.7	$	1.3		$	(391.0	)	$	4,519.00
	Depreciation and Amortization		$	320.2	$	67.1	$	0.8		$	—		$	388.1
	Operating Income (Loss)		$	719.4	$	367.1	$	(6.4	)	$	—		$	1,080.10
	Equity in Earnings of Unconsolidated Affiliates		$	68.5	$	—	$	(0.1	)	$	—		$	68.4
	Interest Expense, Net		$	136.2	$	65.7	$	50.8		$	(0.6	)	$	252.1
	Income Tax Expense (Benefit)		$	243.6	$	120.2	$	(25.9	)	$	—		$	337.9
	Net Income (Loss)		$	425.1	$	181.6	$	577.2		$	(606.5	)	$	577.4
	Capital Expenditures		$	657.9	$	26.1	$	3.4		$	—		$	687.4
	Total Assets (c)		$	14,460.40	$	2,846.50	$	4,719.50		$	(7,257.0	)	$	14,769.40
	December 31, 2012
	Operating Revenues (b)		$	4,190.80	$	439.9	$	1.2		$	(385.5	)	$	4,246.40
	Depreciation and Amortization		$	296.4	$	67.1	$	0.7		$	—		$	364.2
	Operating Income (Loss)		$	647.7	$	358.8	$	(6.2	)	$	—		$	1,000.30
	Equity in Earnings of Unconsolidated Affiliates		$	65.7	$	—	$	(0.2	)	$	—		$	65.5
	Interest Expense, Net		$	129.4	$	66.7	$	52.5		$	(0.4	)	$	248.2
	Income Tax Expense (Benefit)		$	214.9	$	116.6	$	(25.2	)	$	—		$	306.3
	Net Income (Loss)		$	400.6	$	175.9	$	546.1		$	(576.3	)	$	546.3
	Capital Expenditures		$	697.3	$	5.5	$	4.2		$	—		$	707
	Total Assets (c)		$	13,988.10	$	2,903.50	$	4,431.40		$	(7,038.0	)	$	14,285.00
	(a)	Corporate & Other includes all other non-utility activities, primarily non-utility real estate investment and development by Wispark as well as interest on corporate debt.
	(b)	An elimination for intersegment revenues is included in Operating Revenues. This elimination is primarily between We Power and Wisconsin Electric.
	(c)	An elimination of $2,172.9 million, $2,231.2 million and $2,286.7 million is included in Total Assets as of December 31, 2014, 2013 and 2012, respectively, for all PTF-related activity between We Power and Wisconsin Electric.

Related_Parties

Related Parties	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Provided and received services from the associated companies	RELATED PARTIES
	We receive and/or provide certain services to other associated companies in which we have an equity investment.
	American Transmission Company LLC:   As of December 31, 2014, we have a 26.2% interest in ATC. We pay ATC for transmission and other related services it provides. In addition, we provide a variety of operational, maintenance and project management work for ATC, which is reimbursed to us by ATC. We are required to pay the cost of needed transmission infrastructure upgrades for new generation projects while projects are under construction. ATC reimburses us for these costs when new generation is placed in service.
	The following table summarizes material related party transactions with ATC during 2014, 2013 and 2012:
	Equity Investee	2014		2013		2012
		(Millions of Dollars)
	Equity in Earnings	$	66	$	68.5	$	65.7
	Distributions Received	$	57.5	$	54.5	$	52.6
	Services Provided	$	8.1	$	9	$	8.2
	Services Received	$	231.4	$	234.2	$	222.7
	As of December 31, 2014 and 2013, our Consolidated Balance Sheets included receivable and payable balances with ATC as follows:
	Equity Investee	2014		2013
		(Millions of Dollars)
	Accounts Receivable
	Services provided	$	0.6	$	0.6
	Accounts Payable
	Services received	$	19.3	$	19.5

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES
	Operating Leases:   We enter into long-term purchase power contracts to meet a portion of our anticipated increase in future electric energy supply needs. These contracts expire at various times through 2018. Certain of these contracts were deemed to qualify as operating leases. In addition, we have various other operating leases including leases for coal cars.
	Future minimum payments for the next five years and thereafter for our operating lease contracts are as follows:
		(Millions of Dollars)
	2015	$	5.2
	2016	3.9
	2017	3.2
	2018	3.1
	2019	1.2
	Thereafter	21.5
	Total	$	38.1
	Divested Assets:   We provided customary indemnifications to Wisconsin Power and Light Company, a subsidiary of Alliant Energy Corp. in connection with the sale of our interest in Edgewater Generating Unit 5.
	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 manufactured gas plant sites and related disposal sites used by Wisconsin Electric and Wisconsin Gas, and coal combustion product disposal/landfill sites used by Wisconsin Electric, as discussed below. We are working with the 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 Wisconsin Electric, Wisconsin Gas, 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 $15 million to $47 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 December 31, 2014 and 2013, we established reserves of $32.6 million and $36.9 million, respectively, related to future remediation costs.
	Historically, the PSCW has allowed Wisconsin utilities, including Wisconsin Electric and Wisconsin Gas, 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.
	Coal Combustion Product Landfill Sites:   Wisconsin Electric aggressively seeks environmentally acceptable, beneficial uses for its coal combustion products. However, some coal combustion products have been, and to a small degree continue to be, managed in company-owned, licensed landfills. Some early designed and constructed landfills have at times required various levels of monitoring or remediation. Where Wisconsin Electric has become aware of these conditions, efforts have been made to define the nature and extent of any release, and work has been performed to address these conditions. During 2014, 2013 and 2012, Wisconsin Electric incurred $0.1 million, $0.1 million and $0.3 million respectively, in landfill remediation expenses. As of December 31, 2014, we have no reserves established related to coal combustion product landfill sites.
	Valley Power Plant Title V Air Permit:   The WDNR renewed VAPP's Title V operating permit in February 2011. The term of the permit is five years. In March 2011, the Sierra Club petitioned the EPA for additional reductions and monitoring for particulate matter and revisions to certain applicable requirements. No timeline has been set by the EPA to respond to that petition. In May 2012, the Sierra Club filed a notice of intent to bring suit to force the EPA to issue a response to that petition. We believe that the permit was properly issued and that the plant is in compliance with all applicable regulations and standards. However, if as a result of this proceeding the permit is remanded to the WDNR, the plant will continue to operate under the previous operating permit.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
SUPPLEMENTAL CASH FLOW INFORMATION	SUPPLEMENTAL CASH FLOW INFORMATION
	During the year ended December 31, 2014, we paid $241.1 million in interest, net of amounts capitalized, and paid $22.0 million in income taxes, net of refunds. During the year ended December 31, 2013, we paid $250.4 million in interest, net of amounts capitalized, and received $39.6 million in net refunds from income taxes. During the year ended December 31, 2012, we paid $241.2 million in interest, net of amounts capitalized, and received $107.0 million in net refunds from income taxes.
	As of December 31, 2014, 2013 and 2012, the amount of accounts payable related to capital expenditures was $1.8 million, $4.7 million and $15.7 million, respectively.
	During the years ended December 31, 2014, 2013 and 2012, total amortization of deferred revenue was $55.7 million, $56.5 million and $54.9 million, respectively.

Subsequent_Event_Notes

Subsequent Event (Notes)	12 Months Ended
	Dec. 31, 2014
Subsequent Event [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENT
	On January 12, 2015, we entered into an agreement with the Governor of the State of Michigan, the Attorney General of the State of Michigan, the Staff of the MPSC and the owners of two large mines in the Upper Peninsula of Michigan, to resolve all objections these parties raised at the FERC and MPSC related to Wisconsin Energy’s proposed acquisition of Integrys. We believe that this agreement is in the best interest of our customers. In connection with the agreement, we entered into a non-binding term sheet to sell our Michigan electric distribution assets and the Presque Isle Power Plant to a third party. The carrying value of these assets is approximately $292 million as of December 31, 2014.
	We are working to achieve a definitive agreement for the sale of these assets by the end of March 2015. This agreement would be subject to approval by several regulatory agencies including FERC, the PSCW and the MPSC. If we are able to reach a definitive agreement consistent with the financial terms of the non-binding term sheet, we would seek the recovery of approximately $190 million of net unrecovered plant costs from our remaining customers.

Schedule_I_Condensed_Parent_Co

Schedule I -- Condensed Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2014
Schedule I -- Condensed Parent Company Financial Statements [Abstract]
SCHEDULE I - CONDENSED PARENT COMPANY FINANCIAL STATEMENTS	WISCONSIN ENERGY CORPORATION
	INCOME STATEMENTS
	(Parent Company Only)
	SCHEDULE I -- CONDENSED PARENT COMPANY
	FINANCIAL STATEMENTS
		Year Ended December 31
		2014			2013			2012
		(Millions of Dollars)
	Other Income, Net	$	2.8		$	3.1		$	3.2
	Corporate Expense	26.8			5.5			4.8
	Interest Expense	53.1			54.4			55.7
	Loss before Taxes	(77.1		)	(56.8		)	(57.3		)
	Income Tax Benefit	30.4			26.4			26
	Loss after Taxes	(46.7		)	(30.4		)	(31.3		)
	Equity in Subsidiaries' Continuing Operations	635			607.8			577.6
	Net Income	$	588.3		$	577.4		$	546.3
	See accompanying notes to condensed parent company financial statements.
	WISCONSIN ENERGY CORPORATION
	STATEMENTS OF CASH FLOWS
	(Parent Company Only)
	SCHEDULE I - CONDENSED PARENT COMPANY
	FINANCIAL STATEMENTS - (Cont'd)
		Year Ended December 31
		2014			2013			2012
		(Millions of Dollars)
	Operating Activities
	Net income	$	588.3		$	577.4		$	546.3
	Reconciliation to cash
	Equity in subsidiaries' earnings	(635.0		)	(607.8		)	(577.6		)
	Dividends and distributions from subsidiaries	720			720.4			842.3
	Deferred income taxes, net	60.1			(7.8		)	104.4
	Accrued income taxes, net	4.1			66.8			(457.9		)
	Change in - Other current assets	—			(0.1		)	0.2
	Change in - Other current liabilities	5.1			(22.9		)	(6.7		)
	Change in - Accounts receivable	(0.3		)	(2.7		)	22.5
	Other, net	(8.1		)	(21.6		)	(8.1		)
	Cash Provided by Operating Activities	734.2			701.7			465.4
	Investing Activities
	Capital contributions to associated companies	(225.5		)	(195.3		)	(21.5		)
	Capitalized interest and other	5			4			12.6
	Cash Used in Investing Activities	(220.5		)	(191.3		)	(8.9		)
	Financing Activities
	Exercise of stock options	50.3			48.5			49.8
	Purchase of common stock	(123.2		)	(223.4		)	(153.9		)
	Dividends paid on common stock	(352.0		)	(328.9		)	(276.3		)
	Change in short-term debt	(72.0		)	5			(79.5		)
	Change in notes payable due associated companies	3.5			(26.8		)	3.8
	Other, net	16.7			14.6			—
	Cash Used in Financing Activities	(476.7		)	(511.0		)	(456.1		)
	Change in Cash and Cash Equivalents	37			(0.6		)	0.4
	Cash and Cash Equivalents at Beginning of Year	0.3			0.9			0.5
	Cash and Cash Equivalents at End of Year	$	37.3		$	0.3		$	0.9
	See accompanying notes to condensed parent company financial statements.
	WISCONSIN ENERGY CORPORATION
	BALANCE SHEETS
	(Parent Company Only)
	SCHEDULE I - CONDENSED PARENT COMPANY
	FINANCIAL STATEMENTS - (Cont'd)
		December 31
		2014			2013
		(Millions of Dollars)
	Assets
	Current Assets
	Cash and cash equivalents	$	37.3		$	0.3
Accounts and notes receivable from associated companies	37.8			37.4
Prepaid taxes and other	264.2			297.6
Total Current Assets	339.3			335.3
Property and Investments
Investment in subsidiary companies	4,917.80			4,761.80
Other	1.5			1.8
Total Property and Investments	4,919.30			4,763.60
Deferred Charges and Other Assets	118.7			143.2
Total Assets	$	5,377.30		$	5,242.10
Liabilities and Equity
Current Liabilities
Short-term debt	$	—		$	72
Notes payable due associated companies	117.2			113.8
Accrued taxes and other	22.4			11.8
Total Current Liabilities	139.6			197.6
Long-term debt	695.8			695
Other Long-term liabilities	122.2			116.5
Stockholder's equity	4,419.70			4,233.00
Total Liabilities and Equity	$	5,377.30		$	5,242.10
See accompanying notes to condensed parent company financial statements.
WISCONSIN ENERGY CORPORATION
NOTES TO FINANCIAL STATEMENTS
(Parent Company Only)
SCHEDULE I - CONDENSED PARENT COMPANY
FINANCIAL STATEMENTS - (Cont'd)
1.    For Parent Company only presentation, investment in subsidiaries are accounted for using the equity method. The condensed Parent Company financial statements and notes should be read in conjunction with the consolidated financial statements and notes of Wisconsin Energy Corporation appearing in this Annual Report on Form 10-K.
2.    Wisconsin Energy's ability as a holding company to pay common dividends primarily depends on the availability of funds received from the Parent Company's non-utility subsidiary, We Power, and its principal utility subsidiaries, Wisconsin Electric and Wisconsin Gas. During 2014, Wisconsin Electric and Wisconsin Gas collectively provided Wisconsin Energy with $423.0 million of dividends, and We Power provided $297.0 million of distributions.
Various financing arrangements and regulatory requirements impose certain restrictions on the ability of the Parent Company's subsidiaries to transfer funds to the Parent Company in the form of cash dividends, loans or advances. In addition, under Wisconsin law, Wisconsin Electric and Wisconsin Gas are prohibited from loaning funds, either directly or indirectly, to the Parent Company.
Wisconsin Energy does not believe that these restrictions will materially affect the Parent Company's operations or limit any dividend payments in the foreseeable future.
3.    As of December 31, 2014, the maturities of the Parent Company long-term debt outstanding were as follows:
	(Millions of Dollars)
2015	$	—
2016	—
2017	—
2018	—
2019	—
Thereafter	700
Total	$	700
Wisconsin Energy amortizes debt premiums, discounts and debt issuance costs over the lives of the debt and includes the costs in interest expense.
Effective May 2017, the $500 million of Junior Notes will bear interest at the three-month LIBOR Rate plus 211.25 basis points and will reset quarterly.
In December 2014, Wisconsin Energy amended its bank back-up credit facility to extend its expiration from December 2017 to December 2019. The facility contains customary covenants, including certain limitations on Wisconsin Energy's ability to sell assets. The credit facility also contains customary events of default, including payment defaults, material inaccuracy of representations and warranties, covenant defaults, bankruptcy proceedings, certain judgments, ERISA defaults and change of control. In addition, pursuant to the terms of the credit facility, Wisconsin Energy must ensure that certain of its subsidiaries comply with several of the covenants contained therein. In addition, Wisconsin Energy is required to maintain, subject to certain exclusions, a minimum total funded debt to capitalization ratio of less than 70%.
As of December 31, 2014, Wisconsin Energy was in compliance with all covenants.
WECC is a subsidiary of Wisconsin Energy and has $50 million of long-term notes outstanding. In a Support Agreement between WECC and Wisconsin Energy, Wisconsin Energy agreed to make sufficient liquid asset contributions to WECC to permit WECC to service its debt obligations as they become due.
4.    The carrying amount and estimated fair value of certain of our recorded financial instruments as of December 31 are as follows:
		2014						2013
		Carrying			Fair			Carrying		Fair
Financial Instruments		Amount			Value			Amount		Value
		(Millions of Dollars)
Long-term debt including current portion		$	700		$	770		$	700	$	749.4
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 long-term debt, including the current portion of long-term debt, 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 Parent Company's bond rating and the present value of future cash flows.
5.    During the year ended December 31, 2014, Wisconsin Energy paid $44.4 million in interest, net of amounts capitalized, and received $95.1 million in net refunds from income taxes. During the year ended December 31, 2013, Wisconsin Energy paid $44.4 million in interest, net of amounts capitalized, and received $86.1 million in net refunds from income taxes. During the year ended December 31, 2012, Wisconsin Energy paid $45.2 million in interest, net of amounts capitalized, and received $128.2 million in net refunds from income taxes.

Schedule_II_Valuation_and_Qual

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS
	SCHEDULE II	VALUATION AND QUALIFYING ACCOUNTS
	Allowance for Doubtful Accounts		Balance at Beginning of the Period		Expense		Deferral			Net Write-offs			Balance at End of the Period
			(Millions of Dollars)
	December 31, 2014		$	61	$	49.8	$	18.4		$	(54.7	)	$	74.5
	December 31, 2013		$	58	$	49.4	$	0.4		$	(46.8	)	$	61
	December 31, 2012		$	61.7	$	47.7	$	(4.0	)	$	(47.4	)	$	58

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Consolidation	General:   Our consolidated financial statements include the accounts of Wisconsin Energy Corporation (Wisconsin Energy, the Company, our, we or us), a diversified holding company, as well as our subsidiaries in the following reportable segments:
	•	Utility Energy Segment -- Consisting of Wisconsin Electric and Wisconsin Gas, engaged primarily in the generation of electricity and the distribution of electricity and natural gas; and
	•	Non-Utility Energy Segment -- Consisting primarily of We Power, engaged principally in the ownership of electric power generating facilities for long-term lease to Wisconsin Electric.
	Our Corporate and Other segment includes Wispark, which develops and invests in real estate. We have also eliminated all intercompany transactions from the consolidated financial statements.
Basis of Accounting	The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of certain assets and liabilities and disclosure of contingent assets and liabilities at the date of financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Revenues	Revenues:   We recognize energy revenues on the accrual basis and include estimated amounts for services rendered but not billed.
	Our retail electric rates in Wisconsin are established by the PSCW and include base amounts for fuel and purchased power costs. The electric fuel rules in Wisconsin allow us to defer, for subsequent rate recovery or refund, any under-collection or over-collection of fuel costs that are outside of the symmetrical fuel cost tolerance, which the PSCW set at plus or minus 2% of the approved fuel cost plan. The deferred under-collected amounts are subject to an excess revenues test.
	Our retail gas rates include monthly adjustments which permit the recovery or refund of actual purchased gas costs. We defer any difference between actual gas costs incurred (adjusted for a sharing mechanism) and costs recovered through rates as a current asset or liability. The deferred balance is returned to or recovered from customers at intervals throughout the year.
	We recognize We Power revenues (consisting of the lease payments included in rates and the amortization of the deferred revenue) on a levelized basis over the term of the lease.
Accounting For MISO Energy Transactions	Accounting for MISO Energy Transactions:   The MISO Energy Markets operate under both day-ahead and real-time markets. We record energy transactions in the MISO Energy Markets on a net basis for each hour.
Property and Depreciation	Property and Depreciation:   We record property, plant and equipment at cost. Cost includes material, labor, overheads and capitalized interest. Utility property also includes AFUDC - Equity. Additions to and significant replacements of property are charged to property, plant and equipment at cost; minor items are charged to maintenance expense. The cost of depreciable utility property less salvage value is charged to accumulated depreciation when property is retired.
	We recorded the following property in service by segment as of December 31:
	Property In Service		2014		2013
			(Millions of Dollars)
	Utility Energy		$	12,290.70	$	11,779.80
	Non-Utility Energy		3,127.80		3,091.30
	Other		90.5		95.2
	Total		$	15,509.00	$	14,966.30
	Our utility depreciation rates are certified by the PSCW and MPSC and include estimates for salvage value and removal costs. Depreciation as a percent of average depreciable utility plant was 2.9% in 2014, 2013 and 2012.
	We depreciate our We Power assets over the estimated useful life of the various property components. The components have useful lives of between 10 to 45 years for PWGS 1 and PWGS 2, and 10 to 55 years for OC 1 and OC 2.
	Our regulated utilities collect in their rates amounts representing future removal costs for many assets that do not have an associated Asset Retirement Obligation (ARO). We record a regulatory liability on our balance sheet for the estimated amounts we have collected in rates for future removal costs less amounts we have spent in removal activities. This regulatory liability was $741.1 million as of December 31, 2014 and $724.5 million as of December 31, 2013.
	We recorded the following Construction Work in Progress (CWIP) by segment as of December 31:
	CWIP		2014		2013
			(Millions of Dollars)
	Utility Energy		$	170.1	$	132.7
	Non-Utility Energy		21.1		16.5
	Other		0.6		0.4
	Total		$	191.8	$	149.6
Allowance For Funds Used During Construction - Regulated	Allowance For Funds Used During Construction - Regulated:   AFUDC is included in utility plant accounts and represents the cost of borrowed funds (AFUDC - Debt) used during plant construction, and a return on stockholders' capital (AFUDC - Equity) used for construction purposes. AFUDC - Debt is recorded as a reduction of interest expense, and AFUDC - Equity is recorded in Other Income and Deductions, net.
Capitalized Interest And Carrying Costs Non Regulated Energy Policy [Text Block]	Deferred Revenue:   As part of the construction of the PTF electric generating units, we capitalized interest during construction. As allowed under the lease agreements, we were able to collect the carrying costs during the construction of the PTF generating units from our utility customers. The carrying costs that we collected during construction have been recorded as deferred revenue on our balance sheet and we are amortizing the deferred carrying costs to revenue over the individual lease terms.
Earning per Common Share	Earnings per Common Share:   We compute basic earnings per common share by dividing our net income attributed to common shareholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per common share is computed by dividing net income attributed to common shareholders by the weighted average number of common shares outstanding during the period, adjusted for the exercise and/or conversion of all potentially dilutive securities. Such dilutive securities include in-the-money stock options. All stock options outstanding during 2014, 2013 and 2012 were included in the computation of diluted earnings per share. Anti-dilutive shares are excluded from the calculation.
Materials, Supplies and Inventories	Materials, Supplies and Inventories:   Our inventory as of December 31 consists of:
	Materials, Supplies and Inventories		2014		2013
			(Millions of Dollars)
	Fossil Fuel		$	125.6	$	117.7
	Materials and Supplies		150.2		133.9
	Natural Gas in Storage		124.8		77.8
	Total		$	400.6	$	329.4
	Substantially all fossil fuel, materials and supplies, and natural gas in storage inventories are recorded using the weighted-average cost method of accounting.
Regulatory Accounting	Regulatory Accounting:   The economic effects of regulation can result in regulated companies recording costs that have been or are expected to be allowed in the rate-making process in a period different from the period in which the costs would be charged to expense by an unregulated enterprise. When this occurs, costs are deferred as regulatory assets on the balance sheet and expensed in the periods when they are reflected in rates. We defer regulatory assets pursuant to specific or generic orders issued by our regulators. Additionally, regulators can impose regulatory liabilities upon a regulated company for amounts previously collected from customers and for amounts that are expected to be refunded to customers. In general, regulatory assets are recovered in a period between one to eight years. For further information, see Note C.
Asset Retirement Obligations	Asset Retirement Obligations:   We record a liability for a legal ARO in the period in which it is incurred. When a new legal obligation is recorded, we capitalize the costs of the liability by increasing the carrying amount of the related long-lived asset. We accrete the liability to its present value each period and depreciate the capitalized cost over the useful life of the related asset. At the end of the asset's useful life, we settle the obligation for its recorded amount or incur a gain or loss. As it relates to our regulated operations, we apply regulatory accounting guidance and recognize regulatory assets or liabilities for the timing differences between when we recover legal AROs in rates and when we would recognize these costs. For further information, see Note E.
Derivative Financial Instruments	Derivative Financial Instruments:   We have derivative physical and financial instruments which we report at fair value. For further information, see Note L.
Cash and Cash Equivalents	Cash and Cash Equivalents:   Cash and cash equivalents include marketable debt securities acquired three months or less from maturity.
Margin Accounts	Margin Accounts:   Cash deposited in brokerage accounts for margin requirements is recorded in Other Current Assets on our Consolidated Balance Sheets.
Goodwill	Goodwill:   Goodwill reflects the cost of an acquisition in excess of the fair values assigned to identifiable net assets acquired. As of December 31, 2014 and 2013, we had $441.9 million of goodwill recorded at the utility energy segment, which related to our acquisition of Wisconsin Gas in 2000.
	Goodwill is not subject to amortization. However, it is subject to fair value-based rules for measuring impairment, and resulting write-downs, if any, are to be reflected in operating expense. Fair value is assessed by considering future discounted cash flows, a comparison of fair value based on public company trading multiples, and merger and acquisition transaction multiples for similar companies. This evaluation utilizes the information available under the circumstances, including reasonable and supportable assumptions and projections. We perform our annual impairment test as of August 31. There was no impairment to the recorded goodwill balance as of our annual 2014 impairment test date.
Impairment or Disposal of Long Lived Assets	Impairment or Disposal of Long Lived Assets:   We carry property, equipment and goodwill related to businesses held for sale at the lower of cost or estimated fair value less cost to sell. As of December 31, 2014, we had no assets classified as Held for Sale. Long-lived assets are tested for recoverability whenever events or changes in circumstances indicate that their carrying value may not be recoverable from the use and eventual disposition of the asset based on the remaining useful life. An impairment loss is recognized when the carrying amount of an asset is not recoverable and exceeds the fair value of the asset. The carrying amount of an asset is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. An impairment loss is measured as the excess of the carrying amount of the asset in comparison to the fair value of the asset.
Investments	Investments:   We account for investments in other affiliated companies in which we do not maintain control using the equity method of accounting. We had a total ownership interest of approximately 26.2% in ATC as of December 31, 2014 and 2013. We are represented by one out of ten ATC board members, each of whom has one vote. Due to the voting requirements, no individual member has more than 10% of the voting control. For further information regarding such investments, see Note P.
Income Taxes	Income Taxes:   We follow the liability method in accounting for income taxes. Accounting guidance for income taxes requires the recording of deferred assets and liabilities to recognize the expected future tax consequences of events that have been reflected in our financial statements or tax returns and the adjustment of deferred tax balances to reflect tax rate changes. We are required to assess the likelihood that our deferred tax assets would expire before being realized. If we conclude that certain deferred tax assets are likely to expire before being realized, a valuation allowance would be established against those assets. GAAP requires that, if we conclude in a future period that it is more likely than not that some or all of the deferred tax assets would be realized before expiration, we reverse the related valuation allowance in that period. Any change to the allowance, as a result of a change in judgment about the realization of deferred tax assets, is reported in income tax expense.
	Investment tax credits associated with regulated operations are deferred and amortized over the life of the assets. We file a consolidated Federal income tax return. Accordingly, we allocate Federal current tax expense benefits and credits to our subsidiaries based on their separate tax computations. For further information, see Note G.
	We recognize interest and penalties accrued related to unrecognized tax benefits in Income Taxes in our Consolidated Income Statements, as well as Regulatory Assets or Regulatory Liabilities in our Consolidated Balance Sheets.
	We collect sales and use taxes from our customers and remit these taxes to governmental authorities. These taxes are recorded in our Consolidated Income Statements on a net basis.
Stock Options	Stock Options:   We estimate the fair value of stock options using the binomial pricing model. We report unearned stock-based compensation associated with non-vested restricted stock and performance share awards activity within Other Paid in Capital in our Consolidated Statements of Common Equity. We report excess tax benefits as a financing cash inflow. Historically, all stock options have been granted with an exercise price equal to the fair market value of the common stock on the date of grant and expire no later than 10 years from grant date. For a discussion of the impacts to our Consolidated Financial Statements, see Note H.
Treasury Grant Accounting Policy [Policy Text Block]	Treasury Grant:   In December 2013, we filed an application with the United States Treasury for a Section 1603 renewable energy grant related to the construction of our biomass facility in Rothschild, Wisconsin. The PSCW anticipated the recognition of this grant as income when it set rates for the two years beginning January 1, 2013. We provided bill credits to our customers in 2013 and 2014. For the years ended December 31, 2014 and December 31, 2013, $17.4 million and $48.0 million, respectively, was recognized as income, which reflects the amount that was returned to customers in the form of bill credits during the year. The accounting reflects the regulatory treatment of the grant.
	In June 2014, we received approximately $76.2 million related to the Treasury Grant. The PSCW approved escrow accounting for the Treasury Grant and the proceeds we received that exceeded the amounts originally included in rates are being returned to customers in the form of bill credits.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Other Income and Deductions, Net	Other Income and Deductions, Net:   We recorded the following items in Other Income and Deductions, net for the years ended December 31:
	Other Income and Deductions, net		2014			2013				2012
			(Millions of Dollars)
	AFUDC - Equity		$	5.6		$	18.3			$	35.3
	Gain on Property Sales		7.5			0.8				2.7
	Other, net		0.3			(0.3		)		(3.2		)
	Total Other Income and Deductions, net		$	13.4		$	18.8			$	34.8
Property In Service By Segment	Property and Depreciation:   We record property, plant and equipment at cost. Cost includes material, labor, overheads and capitalized interest. Utility property also includes AFUDC - Equity. Additions to and significant replacements of property are charged to property, plant and equipment at cost; minor items are charged to maintenance expense. The cost of depreciable utility property less salvage value is charged to accumulated depreciation when property is retired.
	We recorded the following property in service by segment as of December 31:
	Property In Service		2014			2013
			(Millions of Dollars)
	Utility Energy		$	12,290.70		$	11,779.80
	Non-Utility Energy		3,127.80			3,091.30
	Other		90.5			95.2
	Total		$	15,509.00		$	14,966.30
	Our utility depreciation rates are certified by the PSCW and MPSC and include estimates for salvage value and removal costs. Depreciation as a percent of average depreciable utility plant was 2.9% in 2014, 2013 and 2012.
	We depreciate our We Power assets over the estimated useful life of the various property components. The components have useful lives of between 10 to 45 years for PWGS 1 and PWGS 2, and 10 to 55 years for OC 1 and OC 2.
	Our regulated utilities collect in their rates amounts representing future removal costs for many assets that do not have an associated Asset Retirement Obligation (ARO). We record a regulatory liability on our balance sheet for the estimated amounts we have collected in rates for future removal costs less amounts we have spent in removal activities. This regulatory liability was $741.1 million as of December 31, 2014 and $724.5 million as of December 31, 2013.
	We recorded the following Construction Work in Progress (CWIP) by segment as of December 31:
	CWIP		2014			2013
			(Millions of Dollars)
	Utility Energy		$	170.1		$	132.7
	Non-Utility Energy		21.1			16.5
	Other		0.6			0.4
	Total		$	191.8		$	149.6
Construction Work in Progress (CWIP) by segment	We recorded the following Construction Work in Progress (CWIP) by segment as of December 31:
	CWIP		2014			2013
			(Millions of Dollars)
	Utility Energy		$	170.1		$	132.7
	Non-Utility Energy		21.1			16.5
	Other		0.6			0.4
	Total		$	191.8		$	149.6
Allowance For Funds Used During Construction	Our regulated utility segment recorded the following AFUDC for the years ended December 31:
		2014			2013				2012
		(Millions of Dollars)
	AFUDC - Debt	$	2.3		$	7.7			$	14.7
	AFUDC - Equity	$	5.6		$	18.3			$	35.3
Inventories	Materials, Supplies and Inventories:   Our inventory as of December 31 consists of:
	Materials, Supplies and Inventories		2014			2013
			(Millions of Dollars)
	Fossil Fuel		$	125.6		$	117.7
	Materials and Supplies		150.2			133.9
	Natural Gas in Storage		124.8			77.8
	Total		$	400.6		$	329.4
	Substantially all fossil fuel, materials and supplies, and natural gas in storage inventories are recorded using the weighted-average cost method of accounting.
Fair value of stock options	The fair value of our stock options was calculated using a binomial option-pricing model using the following weighted-average assumptions:
		2014		2013	2012
	Risk-free interest rate	0.1% - 3.0%		0.1% - 1.9%	0.1% - 2.0%
	Dividend yield	3.80%		3.70%	3.90%
	Expected volatility	18.00%		18.00%	19.00%
	Expected life (years)	5.8		5.9	5.9
	Expected forfeiture rate	2.00%		2.00%	2.00%
	Weighted-average fair value
	of our stock options granted	$4.18		$3.45	$3.34
Property In Services By Segment [Text Block]	We recorded the following property in service by segment as of December 31:
	Property In Service		2014			2013
			(Millions of Dollars)
	Utility Energy		$	12,290.70		$	11,779.80
	Non-Utility Energy		3,127.80			3,091.30
	Other		90.5			95.2
	Total		$	15,509.00		$	14,966.30

Regulatory_Assets_and_Liabilit1

Regulatory Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory assets and liabilities	Our regulatory assets and liabilities as of December 31 consist of:
		2014		2013
		(Millions of Dollars)
	Regulatory Assets
	Deferred unrecognized pension costs	$	629.5	$	537.6
	Deferred income tax related	176		169.5
	Escrowed electric transmission costs	146		126.8
	Escrowed PTF	66.6		49.3
	Escrowed conservation	58		66.9
	Deferred plant related -- capital lease	42.3		56.5
	Deferred environmental costs	45.9		47
	Other, net	106.9		54.9
	Total regulatory assets	$	1,271.20	$	1,108.50
	Regulatory Liabilities
	Deferred cost of removal obligations	$	741.1	$	724.5
	Escrowed bad debt costs	30.1		64.6
	Other, net	59.4		90
	Total regulatory liabilities	$	830.6	$	879.1

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
Change in Asset Retirement Obligations	The following table presents the change in our AROs during 2014 and 2013:
		2014			2013
		(Millions of Dollars)
	Balance as of January 1	$	42.3		$	44.3
	Liabilities Settled	(1.1		)	(4.4		)
	Accretion	2.4			2.4
	Balance as of December 31	$	43.6		$	42.3

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Summary of income tax expense	The following table is a summary of income tax expense for each of the years ended December 31:
	Income Taxes		2014				2013				2012
			(Millions of Dollars)
	Current tax expense		$	33.6			$	25.2			$	13.1
	Deferred income taxes, net		329.2				313.8				294.4
	Investment tax credit, net		(1.1		)		(1.1		)		(1.2		)
	Total Income Tax Expense		$	361.7			$	337.9			$	306.3
The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to income before income taxes as a result of the following:	The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to income before income taxes as a result of the following:
			2014							2013						2012
							Effective							Effective					Effective
	Income Tax Expense		Amount				Tax Rate			Amount				Tax Rate		Amount			Tax Rate
			(Millions of Dollars)
	Expected tax at statutory federal tax rates		$	332.5			35	%		$	320.3			35	%	$	298.4		35	%
	State income taxes net of federal tax benefit		50.5				5.3	%		49				5.3	%	43.3			5.1	%
	Production tax credits		(17.4		)		(1.8	)%		(16.7		)		(1.8	)%	(15.9		)	(1.9	)%
	Treasury Grant		(3.8		)		(0.4	)%		(7.4		)		(0.8	)%	—			—	%
	AFUDC - Equity		(1.9		)		(0.2	)%		(6.4		)		(0.7	)%	(12.3		)	(1.4	)%
	Investment tax credit restored		(1.1		)		(0.1	)%		(1.1		)		(0.1	)%	(1.2		)	(0.1	)%
	Domestic production activities deduction		—				—	%		—				—	%	(12.6		)	(1.5	)%
	Other, net		2.9				0.3	%		0.2				—	%	6.6			0.7	%
	Total Income Tax Expense		$	361.7			38.1	%		$	337.9			36.9	%	$	306.3		35.9	%
Components of deferred income taxes classified as net current assets and net long-term liabilities	The components of deferred income taxes classified as net current assets and net long-term liabilities as of December 31 are as follows:
	Deferred Tax Assets		2014				2013
			(Millions of Dollars)
	Current
	Future federal tax benefits		$	221.7			$	309.7
	Employee benefits and compensation		13.7				13.8
	Other		47.7				56
	Total Current Deferred Tax Assets		283.1				379.5
	Non-current
	Deferred revenues		221.3				237
	Employee benefits and compensation		98.2				95.6
	Future federal tax benefits		—				32.5
	Property-related		28.8				28.2
	Construction advances		18.9				18.3
	Other		51.8				62.9
	Total Non-Current Deferred Tax Assets		419				474.5
	Total Deferred Tax Assets		$	702.1			$	854
	Deferred Tax Liabilities		2014				2013
			(Millions of Dollars)
	Current
	Prepaid items		$	40.4			$	69.5
	Total Current Deferred Tax Liabilities		40.4				69.5
	Non-current
	Property-related		2,750.40				2,574.40
	Employee benefits and compensation		242.5				238.5
	Investment in transmission affiliate		188.6				169.9
	Deferred transmission costs		58.5				50.8
	Other		85.7				74.9
	Total Non-current Deferred Tax Liabilities		3,325.70				3,108.50
	Total Deferred Tax Liabilities		$	3,366.10			$	3,178.00
	Consolidated Balance Sheet Presentation		2014				2013
	Current Deferred Tax Asset		$	242.7			$	310
	Non-Current Deferred Tax Liability		$	2,906.70			$	2,634.00
Reconciliation of the beginning and ending amount of unrecognized tax benefits	We previously adopted accounting guidance related to uncertainty in income taxes. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:
		2014				2013
		(Millions of Dollars)
	Balance as of January 1	$	8.4			$	11.3
	Reductions for tax positions of prior years	(1.2		)		(2.9		)
	Balance as of December 31	$	7.2			$	8.4

Common_Equity_Tables

Common Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Recorded pre-tax share-based compensation expense and related tax benefit for share-based awards made to employees and directors	The following table summarizes recorded pre-tax share-based compensation expense and the related tax benefit for share-based awards made to our employees and directors as of December 31:
		2014			2013		2012
		(Millions of Dollars)
	Performance units	$	15.4		$	12.7	$	16.3
	Stock options	3.7			3.9		2.7
	Restricted stock	2.8			2.4		3
	Share-based compensation expense	$	21.9		$	19	$	22
	Related Tax Benefit	$	8.8		$	7.6	$	8.8
Stock option activity	The following is a summary of our stock option activity during 2014:
	Stock Options		Number of Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value (Millions)
	Outstanding as of January 1, 2014		8,089,710		$	26.84
	Granted		899,500		$	41.03
	Exercised		(2,201,821	)	$	22.85
	Forfeited		(17,195	)	$	37.42
	Outstanding as of December 31, 2014		6,770,194		$	29.99	5.7		$	154
	Exercisable as of December 31, 2014		3,890,339		$	24.1	3.9		$	111.4
Stock options outstanding	The following table summarizes information about stock options outstanding as of December 31, 2014:
			Options Outstanding						Options Exercisable
					Weighted-Average						Weighted-Average
	Range of Exercise Prices		Number of Options		Exercise Price		Remaining Contractual Life (Years)		Number of Options		Exercise Price		Remaining Contractual Life (Years)
	$17.10  to  $21.11		1,498,071		$	20.86	3.5		1,498,071		$	20.86	3.5
	$23.88  to  $29.35		2,153,513		$	25.06	3.7		2,153,513		$	25.06	3.7
	$34.88  to  $41.03		3,118,610		$	37.79	8		238,755		$	35.88	7.4
			6,770,194		$	29.99	5.7		3,890,339		$	24.1	3.9
Non-vested options	The following table summarizes information about our non-vested options during 2014:
	Non-Vested Stock Options		Number of Options		Weighted- Average Fair Value
	Non-Vested as of January 1, 2014		2,380,790		$	3.38
	Granted		899,500		$	4.18
	Vested		(383,240	)	$	3.26
	Forfeited		(17,195	)	$	3.56
	Non-Vested as of December 31, 2014		2,879,855		$	3.65
Restricted stock activity	Restricted Shares:   The Compensation Committee has also approved restricted stock grants to certain key employees and directors. The following restricted stock activity occurred during 2014:
	Restricted Shares		Number of Shares		Weighted-Average Market Price
	Outstanding as of January 1, 2014		150,698
	Granted		71,504		$	40.96
	Released		(63,509	)	$	33.02
	Forfeited		(3,214	)	$	38.47
	Outstanding as of December 31, 2014		155,479

Preferred_Stock_Tables

Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Preferred Stock [Abstract]
Preferred Stock [Text Block]	PREFERRED STOCK
	The following table shows preferred stock authorized and outstanding at December 31, 2014 and 2013:
		Shares Authorized	Shares Outstanding	Redemption Price Per Share		Total
						(In Millions)
	Wisconsin Energy
	$.01 par value Preferred Stock	15,000,000	—	—		$	—
	Wisconsin Electric
	$100 par value, Six Per Cent. Preferred Stock	45,000	44,498	—		$	4.4
	$100 par value, Serial Preferred Stock	2,286,500
	3.60% Series		260,000	$	101	26
	$25 par value, Serial Preferred Stock	5,000,000	—	—		—
	Total preferred stock of subsidiary					$	30.4

LongTerm_Debt_and_Capital_Leas1

Long-Term Debt and Capital Lease Obligations (Tables)	12 Months Ended
	Dec. 31, 2014
Long-term Debt and Capital Lease Obligations [Abstract]
Long-term debt outstanding maturities and sinking fund requirements	Debentures and Notes:   As of December 31, 2014, the maturities and sinking fund requirements of our long-term debt outstanding (excluding obligations under capital leases) were as follows:
		(Millions of Dollars)
	2015	$	399.5
	2016	27.4
	2017	29.5
	2018	281.1
	2019	282.7
	Thereafter	3,532.20
	Total	$	4,552.40
Summary of capitalized leased facilities	The following is a summary of our capitalized leased facilities as of December 31:
	Capital Lease Assets		2014			2013
			(Millions of Dollars)
	Leased Facilities
	Long-term power purchase commitment		$	140.3		$	140.3
	Accumulated amortization		(98.3		)	(92.5		)
	Total Leased Facilities		$	42		$	47.8
Future minimum lease payments under capital lease and present value of net minimum lease payments	Future minimum lease payments under our capital lease and the present value of our net minimum lease payments as of December 31, 2014 are as follows:
		(Millions of Dollars)
	2015	$	43.5
	2016	45.1
	2017	13.9
	2018	14.7
	2019	15.5
	Thereafter	41.3
	Total Minimum Lease Payments	174
	Less:  Estimated Executory Costs	(54.7		)
	Net Minimum Lease Payments	119.3
	Less:  Interest	(34.8		)
	Present Value of Net
	Minimum Lease Payments	84.5
	Less:  Due Currently	(24.6		)
		$	59.9

ShortTerm_Debt_Tables

Short-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Short-term Debt [Abstract]
Short-term notes payable balances and their corresponding weighted-average interest rates	Short-term notes payable balances and their corresponding weighted-average interest rates as of December 31 consist of:
			2014					2013
						Interest				Interest
	Short-Term Debt		Balance			Rate		Balance		Rate
			(Millions of Dollars, except for percentages)
	Commercial paper		$	617.6		0.22	%	$	537.4	0.2	%
Commercial paper	The following information relates to commercial paper for the years ended December 31:
		2014			2013
		(Millions of Dollars, except for percentages)
	Maximum Short-Term Debt Outstanding	$	721.4		$	594.5
	Average Short-Term Debt Outstanding	$	468.1		$	359.1
	Weighted-Average Interest Rate	0.18		%	0.25		%

Derivative_Instruments_Tables

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments in balance sheet	We record our current derivative assets on the balance sheet in other current assets and the current portion of the liabilities in other current liabilities. The long-term portion of our derivative assets of $0.6 million is recorded in other deferred charges and other assets, and the long-term portion of our derivative liabilities of $0.8 million is recorded in other deferred credit and other liabilities. Our Consolidated Balance Sheets as of December 31, 2014 and 2013 include:
		December 31, 2014							December 31, 2013
		Derivative				Derivative			Derivative			Derivative
		Asset				Liability			Asset			Liability
		(Millions of Dollars)
	Natural Gas	$	5			$	12.3		$	5.6		$	0.1
	Fuel Oil	—				—			0.6			—
	FTRs	7				—			3.5			—
	Coal	3.3				0.2			2.1			0.2
	Total	$	15.3			$	12.5		$	11.8		$	0.3
Derivative instruments' estimated notional volumes and gain (losses)	Our Consolidated 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) for the years ended December 31 were as follows:
		2014						2013
		Volume		Gains				Volume	Gains (Losses)
				(Millions of Dollars)					(Millions of Dollars)
	Natural Gas	40.5 million Dth		$	7.3			48.6 million Dth	$	(8.5	)
	Fuel Oil	9.2 million gallons		0.5				8.6 million gallons	0.5
	FTRs	26.1 million MWh		12.7				25.3 million MWh	14.9
	Total			$	20.5				$	6.9
Offsetting Assets and Liabilities [Table Text Block]
		2014							2013
		Derivative				Derivative			Derivative			Derivative
		Asset				Liability			Asset			Liability
		(Millions of Dollars)
	Gross Amount Recognized on the Balance Sheet	$	15.3			$	12.5		$	11.8		$	0.3
	Gross Amount Not Offset on Balance Sheet (a)	(0.4		)		(11.5		)	—			—
	Net Amount	$	14.9			$	1		$	11.8		$	0.3
	(a)	Gross Amount Not Offset on Balance Sheet includes cash collateral posted of $10.3 million and zero as of December 31, 2014 and 2013, respectively.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Financial assets and liabilities by level within the fair value hierarchy	The following tables summarize our financial assets and liabilities by level within the fair value hierarchy:
	Recurring Fair Value Measures		As of December 31, 2014
			Level 1			Level 2		Level 3		Total
			(Millions of Dollars)
	Assets:
	Derivatives		$	1.1		$	7.2	$	7	15.3
	Total		$	1.1		$	7.2	$	7	$	15.3
	Liabilities:
	Derivatives		$	11.5		$	1	$	—	$	12.5
	Total		$	11.5		$	1	$	—	$	12.5
	Recurring Fair Value Measures		As of December 31, 2013
			Level 1			Level 2		Level 3		Total
			(Millions of Dollars)
	Assets:
	Derivatives		$	5.7		$	2.6	$	3.5	$	11.8
	Total		$	5.7		$	2.6	$	3.5	$	11.8
	Liabilities:
	Derivatives		$	—		$	0.3	$	—	$	0.3
	Total		$	—		$	0.3	$	—	$	0.3
Fair value of derivatives classified as Level 3 in the fair value hierarchy	The following table summarizes the changes to derivatives classified as Level 3 in the fair value hierarchy:
		2014			2013
		(Millions of Dollars)
	Balance as of January 1	$	3.5		$	4.7
	Realized and unrealized gains (losses)	—			—
	Purchases	15.6			10.6
	Issuances	—			—
	Settlements	(12.1		)	(11.8		)
	Transfers in and/or out of Level 3	—			—
	Balance as of December 31	$	7		$	3.5
Carrying amount and estimated fair value of certain financial instruments	The carrying amount and estimated fair value of certain of our recorded financial instruments as of December 31 are as follows:
			2014					2013
			Carrying			Fair		Carrying		Fair
	Financial Instruments		Amount			Value		Amount		Value
			(Millions of Dollars)
	Preferred stock, no redemption required		$	30.4		$	27.1	$	30.4	$	26
	Long-term debt including current portion		$	4,552.40		$	5,126.00	$	4,626.70	$	4,911.80

Benefits_Tables

Benefits (Tables)	12 Months Ended
	Dec. 31, 2014
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Details about pension and OPEB plans	The following table presents details about our pension and OPEB plans:
		Pension							OPEB
		2014				2013			2014			2013
		(Millions of Dollars)
	Change in Benefit Obligation
	Benefit Obligation at January 1	$	1,410.20			$	1,508.50		$	362.7		$	381.2
	Service cost	10.1				14.6			8.5			10
	Interest cost	68.1				60.4			17.8			15.6
	Participants' contributions	—				—			9.1			8.9
	Plan amendments	—				(1.0		)	(4.6		)	—
	Actuarial loss (gain)	120.4				(81.9		)	29.4			(27.7		)
	Gross benefits paid	(103.3		)		(90.4		)	(26.4		)	(26.3		)
	Federal subsidy on benefits paid	N/A				N/A			1.2			1
	Benefit Obligation at December 31	$	1,505.50			$	1,410.20		$	397.7		$	362.7
	Change in Plan Assets
	Fair Value at January 1	$	1,451.00			$	1,385.40		$	327.6		$	285.4
	Actual earnings on plan assets	88.5				147.3			17.7			45.5
	Employer contributions	8.4				8.7			5.5			14.1
	Participants' contributions	—				—			9.1			8.9
	Gross benefits paid	(103.3		)		(90.4		)	(26.4		)	(26.3		)
	Fair Value at December 31	$	1,444.60			$	1,451.00		$	333.5		$	327.6
	Net liability (asset)	$	60.9			$	(40.8	)	$	64.2		$	35.1
Amounts recognized in Consolidated Balance Sheets	Amounts recognized in our Consolidated Balance Sheets as of December 31 related to the funded status of the benefit plans consisted of:
		Pension							OPEB
		2014				2013			2014			2013
		(Millions of Dollars)
	Other long-term assets	$	39.2			$	138.7		$	39.5		$	40.2
	Other long-term liabilities	100.1				97.9			103.7			75.3
	Net liability (asset)	$	60.9			$	(40.8	)	$	64.2		$	35.1
Amounts not yet been recognized in net periodic benefit cost	The following table shows the amounts that have not yet been recognized in our net periodic benefit cost as of December 31 and are recorded as a regulatory asset on our balance sheet:
		Pension							OPEB
		2014				2013			2014			2013
		(Millions of Dollars)
	Net actuarial loss	$	622.7			$	528.8		$	44.1		$	9.8
	Prior service costs (credits)	6.8				8.8			(4.6		)	(1.7		)
	Total - Regulatory Assets	$	629.5			$	537.6		$	39.5		$	8.1
Components of net periodic pension and OPEB costs	The components of net periodic pension and OPEB costs for the years ended December 31 are as follows:
		Pension										OPEB
		2014				2013			2012			2014			2013			2012
		(Millions of Dollars)
	Net Periodic Benefit Cost
	Service cost	$	10.1			$	14.6		$	21.7		$	8.5		$	10		$	10.3
	Interest cost	68.1				60.4			65.5			17.8			15.6			20.3
	Expected return on plan assets	(98.6		)		(95.8		)	(89.6		)	(23.7		)	(21.3		)	(19.0		)
	Amortization of:
	Transition obligation	—				—			—			—			—			0.3
	Prior service cost (credit)	2.1				2.3			2.2			(1.8		)	(2.0		)	(1.9		)
	Actuarial loss	36.7				54.5			41			1.2			3.7			7.3
	Settlement charge	—				2.5			—			—			—			—
	Other	—				—			0.4			—			—			—
	Net Periodic Benefit Cost	$	18.4			$	38.5		$	41.2		$	2		$	6		$	17.3
		Pension						OPEB
		2014		2013		2012		2014	2013		2012
	Weighted-Average assumptions used to
	determine benefit obligations as of Dec. 31
	Discount rate	4.15%		5.00%		4.10%		4.20%	4.95%		4.15%
	Rate of compensation increase	4.00%		4.00%		4.00%		N/A	N/A		N/A
	Weighted-Average assumptions used to
	determine net cost for year ended Dec. 31
	Discount rate	5.00%		4.10%		5.05%		4.95%	4.15%		5.20%
	Expected return on plan assets	7.25%		7.25%		7.25%		7.50%	7.50%		7.50%
	Rate of compensation increase	4.00%		4.00%		4.00%		N/A	N/A		N/A
	Assumed health care cost trend rates as of Dec. 31		2014		2013		2012
	Health care cost trend rate assumed for next year (Pre 65 / Post 65)		7.5%/7.5%		7.5%/7.5%		7.5%/7.5%
	Rate that the cost trend rate gradually adjusts to		5.00%		5.00%		5.00%
	Year that the rate reaches the rate it is assumed to remain at (Pre 65 / Post 65)		2021/2021		2021/2021		2017/2017
	The expecte
A one-percentage-point change in assumed health care cost trend rates effects	A one-percentage-point change in assumed health care cost trend rates would have the following effects:
		1% Increase				1% Decrease
		(Millions of Dollars)
	Effect on
	Post-retirement benefit obligation	$	30.2			$	(25.4	)
	Total of service and interest cost components	$	3.1			$	(2.5	)
Summary of fair value of plan assets by asset category within fair value hierarchy	The following table summarizes the fair value of our pension plan assets by asset category within the fair value hierarchy (for further level information, see Note M):
			As of December 31, 2014
	Asset Category - Pension		Level 1				Level 2			Level 3			Total
			(Millions of Dollars)
	Cash and Cash Equivalents		$	6.4			$	—		$	—		$	6.4
	Equities:
	U.S. Equity		503.8				—			—			503.8
	International Equity		128.6				29.8			—			158.4
	Fixed Income
	Short, Intermediate and Long-term Bonds (a)
	U.S. Bonds		42.5				599.3			—			641.8
	International Bonds		79.3				43.3			—			122.6
	Private Equity and Real Estate		—				—			11.6			11.6
	Total		$	760.6			$	672.4		$	11.6		$	1,444.60
			As of December 31, 2013
	Asset Category - Pension		Level 1				Level 2			Level 3			Total
			(Millions of Dollars)
	Cash and Cash Equivalents		$	21			$	—		$	—		$	21
	Equities:
	U.S. Equity		519.5				—			—			519.5
	International Equity		146.2				35.7			—			181.9
	Fixed Income
	Short, Intermediate and Long-term Bonds (a)
	U.S. Bonds		108.4				505.2			—			613.6
	International Bonds		78.1				36.9			—			115
	Total		$	873.2			$	577.8		$	—		$	1,451.00
	(a)	This category represents investment grade bonds of U.S. and foreign issuers denominated in U.S. dollars from diverse industries.
	The following table summarizes the fair value of our OPEB plan assets by asset category within the fair value hierarchy:
			As of December 31, 2014
	Asset Category - OPEB		Level 1				Level 2			Level 3			Total
			(Millions of Dollars)
	Cash and Cash Equivalents		$	1.4			$	—		$	—		$	1.4
	Equities:
	U.S. Equity		146				—			—			146
	International Equity		42.2				2.5			—			44.7
	Fixed Income:
	Short, Intermediate and Long-term Bonds (a)
	U.S. Bonds		3.5				112.4			—			115.9
	International Bonds		17.5				7			—			24.5
	Private Equity and Real Estate		—				—			1			1
	Total		$	210.6			$	121.9		$	1		$	333.5
			As of December 31, 2013
	Asset Category - OPEB		Level 1				Level 2			Level 3			Total
			(Millions of Dollars)
	Cash and Cash Equivalents		$	2.6			$	—		$	—		$	2.6
	Equities:
	U.S. Equity		148				—			—			148
	International Equity		46.9				2.8			—			49.7
	Fixed Income:
	Short, Intermediate and Long-term Bonds (a)
	U.S. Bonds		8.4				96.3			—			104.7
	International Bonds		16.8				5.8			—			22.6
	Total		$	222.7			$	104.9		$	—		$	327.6
	(a)	This category represents investment grade bonds of U.S. and foreign issuers denominated in U.S. dollars from diverse industries.
Employer contributions to defined benefit plan	Cash Flows:
	Historical employer contributions:
			Pension
	Year		Qualified				Non-Qualified			OPEB
			(Millions of Dollars)
	2012		$	95.6			$	7.1		$	17.7
	2013		$	—			$	8.7		$	14.1
	2014		$	—			$	8.4		$	5.5
Expected benefit payments in future	Estimated benefit payments:
	Year		Pension				Gross OPEB
			(Millions of Dollars)
	2015		$	104.7			$	25.5
	2016		$	103.6			$	22.3
	2017		$	104.3			$	22.8
	2018		$	102.3			$	23.3
	2019		$	102.4			$	24.1
	2020-2024		$	491.8			$	122.5

Segment_Reporting_Tables

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Financial information of reportable operating segments	Summarized financial information concerning our reportable segments for each of the three years ended December 31, 2014 is shown in the following table.
			Reportable Segments							Eliminations
			Energy				Corporate &			& Reconciling			Total
	Year Ended		Utility		Non-Utility		Other (a)			Items			Consolidated
			(Millions of Dollars)
	December 31, 2014
	Operating Revenues (b)		$	4,941.30	$	447.1	$	1.3		$	(392.6	)	$	4,997.10
	Depreciation and Amortization		$	340.6	$	67.5	$	0.7		$	—		$	408.8
	Operating Income (Loss)		$	770.2	$	368.2	$	(26.3	)	$	—		$	1,112.10
	Equity in Earnings of Unconsolidated Affiliates		$	66	$	—	$	(0.1	)	$	—		$	65.9
	Interest Expense, Net		$	128.8	$	64.6	$	48.8		$	(0.7	)	$	241.5
	Income Tax Expense (Benefit)		$	268.9	$	121.4	$	(28.6	)	$	—		$	361.7
	Net Income (Loss)		$	447.2	$	182.8	$	588		$	(629.7	)	$	588.3
	Capital Expenditures		$	689.9	$	41.1	$	5.1		$	—		$	736.1
	Total Assets (c)		$	14,912.80	$	2,821.80	$	4,880.30		$	(7,451.5	)	$	15,163.40
	December 31, 2013
	Operating Revenues (b)		$	4,462.00	$	446.7	$	1.3		$	(391.0	)	$	4,519.00
	Depreciation and Amortization		$	320.2	$	67.1	$	0.8		$	—		$	388.1
	Operating Income (Loss)		$	719.4	$	367.1	$	(6.4	)	$	—		$	1,080.10
	Equity in Earnings of Unconsolidated Affiliates		$	68.5	$	—	$	(0.1	)	$	—		$	68.4
	Interest Expense, Net		$	136.2	$	65.7	$	50.8		$	(0.6	)	$	252.1
	Income Tax Expense (Benefit)		$	243.6	$	120.2	$	(25.9	)	$	—		$	337.9
	Net Income (Loss)		$	425.1	$	181.6	$	577.2		$	(606.5	)	$	577.4
	Capital Expenditures		$	657.9	$	26.1	$	3.4		$	—		$	687.4
	Total Assets (c)		$	14,460.40	$	2,846.50	$	4,719.50		$	(7,257.0	)	$	14,769.40
	December 31, 2012
	Operating Revenues (b)		$	4,190.80	$	439.9	$	1.2		$	(385.5	)	$	4,246.40
	Depreciation and Amortization		$	296.4	$	67.1	$	0.7		$	—		$	364.2
	Operating Income (Loss)		$	647.7	$	358.8	$	(6.2	)	$	—		$	1,000.30
	Equity in Earnings of Unconsolidated Affiliates		$	65.7	$	—	$	(0.2	)	$	—		$	65.5
	Interest Expense, Net		$	129.4	$	66.7	$	52.5		$	(0.4	)	$	248.2
	Income Tax Expense (Benefit)		$	214.9	$	116.6	$	(25.2	)	$	—		$	306.3
	Net Income (Loss)		$	400.6	$	175.9	$	546.1		$	(576.3	)	$	546.3
	Capital Expenditures		$	697.3	$	5.5	$	4.2		$	—		$	707
	Total Assets (c)		$	13,988.10	$	2,903.50	$	4,431.40		$	(7,038.0	)	$	14,285.00
	(a)	Corporate & Other includes all other non-utility activities, primarily non-utility real estate investment and development by Wispark as well as interest on corporate debt.
	(b)	An elimination for intersegment revenues is included in Operating Revenues. This elimination is primarily between We Power and Wisconsin Electric.
	(c)	An elimination of $2,172.9 million, $2,231.2 million and $2,286.7 million is included in Total Assets as of December 31, 2014, 2013 and 2012, respectively, for all PTF-related activity between We Power and Wisconsin Electric.

Related_Parties_Material_relat

Related Parties Material related party transactions (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Provided and received services from the associated companies	RELATED PARTIES
	We receive and/or provide certain services to other associated companies in which we have an equity investment.
	American Transmission Company LLC:   As of December 31, 2014, we have a 26.2% interest in ATC. We pay ATC for transmission and other related services it provides. In addition, we provide a variety of operational, maintenance and project management work for ATC, which is reimbursed to us by ATC. We are required to pay the cost of needed transmission infrastructure upgrades for new generation projects while projects are under construction. ATC reimburses us for these costs when new generation is placed in service.
	The following table summarizes material related party transactions with ATC during 2014, 2013 and 2012:
	Equity Investee	2014		2013		2012
		(Millions of Dollars)
	Equity in Earnings	$	66	$	68.5	$	65.7
	Distributions Received	$	57.5	$	54.5	$	52.6
	Services Provided	$	8.1	$	9	$	8.2
	Services Received	$	231.4	$	234.2	$	222.7
	As of December 31, 2014 and 2013, our Consolidated Balance Sheets included receivable and payable balances with ATC as follows:
	Equity Investee	2014		2013
		(Millions of Dollars)
	Accounts Receivable
	Services provided	$	0.6	$	0.6
	Accounts Payable
	Services received	$	19.3	$	19.5
Receivable and payable balances with ATC	As of December 31, 2014 and 2013, our Consolidated Balance Sheets included receivable and payable balances with ATC as follows:
	Equity Investee	2014		2013
		(Millions of Dollars)
	Accounts Receivable
	Services provided	$	0.6	$	0.6
	Accounts Payable
	Services received	$	19.3	$	19.5
Material related party transactions with ATC [Table Text Block]	The following table summarizes material related party transactions with ATC during 2014, 2013 and 2012:
	Equity Investee	2014		2013		2012
		(Millions of Dollars)
	Equity in Earnings	$	66	$	68.5	$	65.7
	Distributions Received	$	57.5	$	54.5	$	52.6
	Services Provided	$	8.1	$	9	$	8.2
	Services Received	$	231.4	$	234.2	$	222.7

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future minimum payments for the next five years and thereafter for our operating lease contracts	Future minimum payments for the next five years and thereafter for our operating lease contracts are as follows:
		(Millions of Dollars)
	2015	$	5.2
	2016	3.9
	2017	3.2
	2018	3.1
	2019	1.2
	Thereafter	21.5
	Total	$	38.1

Recovered_Sheet1

Summary Of Significant Accounting Policies (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Public Utility Property Plant And Equipment [Line Items]
Disposal Group, Including Discontinued Operation, Long Lived Assets	$0
Public Utilities, Disclosure of Rate Matters	Our retail electric rates in Wisconsin are established by the PSCW and include base amounts for fuel and purchased power costs. The electric fuel rules in Wisconsin allow us to defer, for subsequent rate recovery or refund, any under-collection or over-collection of fuel costs that are outside of the symmetrical fuel cost tolerance, which the PSCW set at plus or minus 2% of the approved fuel cost plan. The deferred under-collected amounts are subject to an excess revenues test. Our retail gas rates include monthly adjustments which permit the recovery or refund of actual purchased gas costs. We defer any difference between actual gas costs incurred (adjusted for a sharing mechanism) and costs recovered through rates as a current asset or liability. The deferred balance is returned to or recovered from customers at intervals throughout the year.
Goodwill	441.9	441.9
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.90%	2.90%	2.90%
Regulatory liabilities	830.6	879.1
Equity Method Investment, Ownership Percentage	50.00%
PWGS 1 [Member]
Public Utility Property Plant And Equipment [Line Items]
Depreciation over an estimated useful life	10 to 45 years
PWGS 2 [Member]
Public Utility Property Plant And Equipment [Line Items]
Depreciation over an estimated useful life	10 to 45 years
OC 1 [Member]
Public Utility Property Plant And Equipment [Line Items]
Depreciation over an estimated useful life	10 to 55 years
OC 2 [Member]
Public Utility Property Plant And Equipment [Line Items]
Depreciation over an estimated useful life	10 to 55 years
Asset Retirement Obligation Costs [Member]
Public Utility Property Plant And Equipment [Line Items]
Regulatory liabilities	$741.10	$724.50
Transmission Affiliate [Member]
Public Utility Property Plant And Equipment [Line Items]
Equity Method Investment, Ownership Percentage		26.20%
Maximum [Member]
Public Utility Property Plant And Equipment [Line Items]
Risk-free interest rate	3.00%	1.90%	2.00%
Minimum [Member]
Public Utility Property Plant And Equipment [Line Items]
Risk-free interest rate	0.10%	0.10%	0.10%

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details 1)	12 Months Ended
	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
ATC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	26.20%
Voting rights in ATC board members	one out of ten
Number of votes with each member of ATC	1
Maximum voting control for individual member in ATC	10.00%

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Property in Service by Segment
Property In Service	$15,509	$14,966.30
Construction Work in Progress (CWIP) by segment
Construction Work in Progress (CWIP)	191.8	149.6
Goodwill related to acquisition of Wisconsin Gas	441.9	441.9
Utility Energy [Member]
Property in Service by Segment
Property In Service	12,290.70	11,779.80
Construction Work in Progress (CWIP) by segment
Construction Work in Progress (CWIP)	170.1	132.7
Non-Utility Energy [Member]
Property in Service by Segment
Property In Service	3,127.80	3,091.30
Construction Work in Progress (CWIP) by segment
Construction Work in Progress (CWIP)	21.1	16.5
Corporate and Other [Member]
Property in Service by Segment
Property In Service	90.5	95.2
Construction Work in Progress (CWIP) by segment
Construction Work in Progress (CWIP)	$0.60	$0.40

Summary_of_Significant_Account5

Summary of Significant Accounting Policies (Details 3) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Debt Securities In Cash Equivalents, Maximum Period Until Maturity	0 years 3 months
Fuel Cost Tolerance Range Set by Regulators, Percent	2.00%
Regulatory liabilities	$830.60	$879.10
Fair value of stock options
Dividend yield	3.80%	3.70%	3.90%
Expected volatility	18.00%	18.00%	19.00%
Expected life (years)	5 years 10 months	5 years 11 months	5 years 11 months
Expected forfeiture rate	2.00%	2.00%	2.00%
Weighted average fair value of our stock options granted	$4.18	$3.45	$3.34
Other Income and Deductions, Net
AFUDC - Equity	5.6	18.3	35.3
Gain on Property Sales	7.5	0.8	2.7
Other, net	0.3	-0.3	-3.2
Other Income and Deductions, net	13.4	18.8	34.8
Allowance For Funds Used During Construction
AFUDC - Debt	2.3	7.7	14.7
AFUDC - Equity	5.6	18.3	35.3
Inventories
Fossil Fuel	125.6	117.7
Materials and Supplies	150.2	133.9
Natural Gas in Storage	124.8	77.8
Total	400.6	329.4
Summary Of Significant Accounting Policies (Additional) (Textuals) [Abstract]
Symmetrical Fuel Cost Tolerance Range Set By Regulatory Authority	Our retail electric rates in Wisconsin are established by the PSCW and include base amounts for fuel and purchased power costs. The electric fuel rules in Wisconsin allow us to defer, for subsequent rate recovery or refund, any under-collection or over-collection of fuel costs that are outside of the symmetrical fuel cost tolerance, which the PSCW set at plus or minus 2% of the approved fuel cost plan. The deferred under-collected amounts are subject to an excess revenues test. Our retail gas rates include monthly adjustments which permit the recovery or refund of actual purchased gas costs. We defer any difference between actual gas costs incurred (adjusted for a sharing mechanism) and costs recovered through rates as a current asset or liability. The deferred balance is returned to or recovered from customers at intervals throughout the year.
Depreciation percentage of average depreciable utility plant	2.90%	2.90%	2.90%
Maximum duration to recover outstanding regulatory assets	8 years
Minimum duration to recover outstanding regulatory assets	1 year
Impairment charges related to goodwill	0
Long-lived assets held for sale	0
Treasury Grant	$17.40	$48	$0
Grant Revenue Received	76.2
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration of options from time of grant				10 years
Fair value of stock options
Weighted average fair value of our stock options granted	$41.03

Regulatory_Assets_and_Liabilit2

Regulatory Assets and Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Regulatory Assets [Line Items]
Regulatory assets earnings return based on short-term rates	$115.10
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	12.8
Regulatory Assets
Regulatory Assets	1,271.20	1,108.50
Escrowed PTF [Member]
Regulatory Assets
Regulatory Assets	66.6	49.3
Deferred unrecognized pension costs [Member]
Regulatory Assets
Regulatory Assets	629.5	537.6
Deferred income tax related [Member]
Regulatory Assets
Regulatory Assets	176	169.5
Escrowed electric transmission costs [Member]
Regulatory Assets
Regulatory Assets	146	126.8
Escrowed conservation [Member]
Regulatory Assets
Regulatory Assets	58	66.9
Deferred plant related -- capital lease [Member]
Regulatory Assets
Regulatory Assets	42.3	56.5
Deferred environmental costs [Member]
Regulatory Assets
Regulatory Assets	45.9	47
Other, net [Member]
Regulatory Assets
Regulatory Assets	$106.90	$54.90

Regulatory_Assets_and_Liabilit3

Regulatory Assets and Liabilities (Details 1) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Regulatory Liabilities [Line Items]
Regulatory liabilities	$830.60	$879.10
Deferred cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	741.1	724.5
Escrowed Bad Debt Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	30.1	64.6
Other, net [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$59.40	$90

Acquisition_Details

Acquisition (Details) (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014
Business Acquisition [Line Items]
Estimate of acquisition-related debt	$1.50
Business Acquisition, Date of Acquisition Agreement	22-Jun-14
Number of WEC shares per Integrys share	1.128
Cash per share of Integrys common stock	$18.58
Estimate of number of WEC shares to be issued for acquisition	91,000,000

Asset_Retirement_Obligations_D

Asset Retirement Obligations (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Change in Asset Retirement Obligations
Balance as of January 1	$42.30	$44.30
Liabilities settled	-1.1	-4.4
Accretion	2.4	2.4
Balance as of December 31	$43.60	$42.30

Variable_Interest_Entities_Det

Variable Interest Entities (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Megawatt
Variable Interest Entities (Textuals)
Power capacity from a gas-fired cogeneration facility under capital lease (MW)	236
Capital lease agreement with VIE remaining term in years	8 years
Total payments over remaining terms of the two agreements	$174
Total capacity and minimum lease payments	$53	$50.30	$45.80

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of income tax expense
Current tax expense (benefit)	$33.60	$25.20	$13.10
Deferred income taxes, net	329.2	313.8	294.4
Investment tax credit, net	-1.1	-1.1	-1.2
Total Income Tax Expense, Amount	361.7	337.9	306.3
The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to income before income taxes as a result of the following:
Expected tax at statutory federal tax rates, Amount	332.5	320.3	298.4
Expected tax at statutory federal tax rates, Effective Tax Rate	35.00%	35.00%	35.00%
State income taxes net of federal tax benefit, Amount	50.5	49	43.3
State income taxes net of federal tax benefit, Effective Tax Rate	5.30%	5.30%	5.10%
Domestic production activities deduction, Amount	0	0	-12.6
Domestic production activities deduction, Effective Tax Rate	0.00%	0.00%	-1.50%
AFUDC - Equity, Amount	-1.9	-6.4	-12.3
AFUDC - Equity, Effective Tax Rate	-0.20%	-0.70%	-1.40%
Production tax credits, Amount	-17.4	-16.7	-15.9
Production tax credits, Effective Tax Rate	-1.80%	-1.80%	-1.90%
Effective Tax Rate Reconciliation, 1603 Grant, Amount	-3.8	-7.4	0
Effective Tax Rate Reconciliation, 1603 Grant, Percent	-0.40%	-0.80%	0.00%
Investment tax credit restored, Amount	-1.1	-1.1	-1.2
Investment tax credit restored, Effective Tax Rate	-0.10%	-0.10%	-0.10%
Other, net, Amount	2.9	0.2	6.6
Other, net, Effective Tax Rate	0.30%	0.00%	0.70%
Total Income Tax Expense, Amount	361.7	337.9	306.3
Total Income Tax Expense, Effective Tax Rate	38.10%	36.90%	35.90%
Current
Deferred Tax Assets, Future Federal Tax Benefits, Current	221.7	309.7
Employee benefits and compensation	13.7	13.8
Other	47.7	56
Total Current Deferred Tax Assets	283.1	379.5
Non-current
Deferred revenues	221.3	237
Employee benefits and compensation	98.2	95.6
Deferred Tax Assets, Future Federal Tax Benefits, Non Current	0	32.5
Property-related	28.8	28.2
Construction advances	18.9	18.3
Other	51.8	62.9
Total Non-current Deferred Tax Assets	419	474.5
Total Deferred Tax Assets	702.1	854
Current
Prepaid items	40.4	69.5
Total Current Deferred Tax Liabilities	40.4	69.5
Non-current
Property-related	2,750.40	2,574.40
Employee benefits and compensation	242.5	238.5
Investment in transmission affiliate	188.6	169.9
Deferred transmission costs	58.5	50.8
Other	85.7	74.9
Total Non-current Deferred Tax Liabilities	3,325.70	3,108.50
Total Deferred Tax Liabilities	3,366.10	3,178
Consolidated Balance Sheet Presentation
Current Deferred Tax Asset	242.7	310
Non-Current Deferred Tax Liability	2,906.70	2,634
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance, January 1	8.4	11.3
Reductions for tax positions of prior years	-1.2	-2.9
Balance, December 31	7.2	8.4	11.3
Income Taxes (Textuals)
Deferred tax assets valuation allowance	7.2	8.4
Net amount of unrecognized tax benefits having impact on the effective tax rate for continuing operations	0	0
Accrued interest in the Consolidated Income Statements	0.3	0.2	0.2
Accrued penalties in the Consolidated Income Statements	0	0	0
Accrued interest on the Consolidated Balance Sheets	0.7	0.4
Accrued penalties on the Consolidated Balance Sheets	0	0
Operating Loss Carryforwards	416.2	810.3
Deferred Tax Assets, Operating Loss Carryforwards	145.7	283.6
Tax Credit Carryforward, Amount	76	58.6
Tax Credit Carryforward, Deferred Tax Asset	$76	$58.60

Common_Equity_Details

Common Equity (Details) (USD $)	12 Months Ended				1 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common Stock, Shares Authorized	325,000,000	325,000,000
Recorded pre-tax share-based compensation expense and related tax benefit for share-based awards made to employees and directors
Share-based compensation expense	$21.90	$19	$22
Common Equity (Textuals)
Actual tax benefit realized for the tax deductions from option exercises/settlement	19.9	17.8	0
Common Stock, Shares, Outstanding	225,517,339	225,962,959
Related Tax Benefit	8.8	7.6	8.8
Maximum [Member]
Common Equity (Textuals)
Requirement to maintain common equity ratio by Wisconsin Electric				53.50%
Requirement to maintain common equity ratio by Wisconsin Gas				52.00%
Minimum [Member]
Common Equity (Textuals)
Requirement to maintain common equity ratio by Wisconsin Electric				48.50%
Requirement to maintain common equity ratio by Wisconsin Gas				47.00%
Performance Units [Member]
Recorded pre-tax share-based compensation expense and related tax benefit for share-based awards made to employees and directors
Share-based compensation expense	15.4	12.7	16.3
Related Tax Benefit	4.8	5.3	7
Restricted stock activity
Granted, Number of Shares					195,365	233,735	239,120	346,570
Common Equity (Textuals)
Unrecognized total compensation costs related share based compensation	12.6
Months, on a weighted-average basis, expected for recognizing total compensation costs related to non-vested stock options	20 months
Intrinsic Value	13.2	14.8	19.3
Stock Options [Member]
Recorded pre-tax share-based compensation expense and related tax benefit for share-based awards made to employees and directors
Share-based compensation expense	3.7	3.9	2.7
Non-Vested Options [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, Nonvested, Weighted Average Grant Date Fair Value		$3.38
Common Equity (Textuals)
Unrecognized total compensation costs related share based compensation	2.1
Months, on a weighted-average basis, expected for recognizing total compensation costs related to non-vested stock options	19 months
Restricted Stock [Member]
Recorded pre-tax share-based compensation expense and related tax benefit for share-based awards made to employees and directors
Share-based compensation expense	2.8	2.4	3
Related Tax Benefit	1	1.3	0
Restricted stock activity
Outstanding	150,698			155,479	155,479	150,698
Granted, Number of Shares	71,504				60,164
Granted, Weighted-Average Market Price	$40.96
Released, Number of Shares	-63,509
Released, Weighted-Average Market Price	$33.02
Forfeited, Number of Shares	-3,214
Forfeited, Weighted-Average Market Price	$38.47
Outstanding	155,479	150,698
Common Equity (Textuals)
Unrecognized total compensation costs related share based compensation	2.8
Months, on a weighted-average basis, expected for recognizing total compensation costs related to non-vested stock options	20 months
Restricted stock vesting period in years						3 years
Intrinsic Value	$2.70	$4	$3.50

Common_Equity_Details_1

Common Equity (Details 1) (USD $)	1 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Jan. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock option activity
Outstanding, Shares, Beginning Balance	6,770,194
Outstanding, Weighted-Average Exercise Price, Beginning	$29.99
Granted, shares	516,475
Granted, Weighted-Average Exercise Price		$4.18	$3.45	$3.34
Outstanding, Shares, Ending Balance		6,770,194
Outstanding, Weighted-Average Exercise Price, Ending		$29.99
Exercisable, shares		3,890,339
Exercisable, Weighted-Average Exercise Price		$24.10
Stock Options [Member]
Stock option activity
Outstanding, Shares, Beginning Balance		8,089,710
Outstanding, Weighted-Average Exercise Price, Beginning		$26.84
Granted, Weighted-Average Exercise Price		$41.03
Exercised, shares		-2,201,821
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price		$22.85
Forfeited, shares		-17,195
Forfeited, Weighted-Average Exercise Price		$37.42
Outstanding, Shares, Ending Balance		6,770,194
Outstanding, Weighted-Average Exercise Price, Ending		$29.99
Outstanding, Weighted-Average Remaining Contractual Life (Years)		5 years 8 months
Outstanding, Aggregate Intrinsic Value		$154
Exercisable, shares		3,890,339
Exercisable, Weighted-Average Exercise Price		$24.10
Exercisable, Weighted-Average Remaining Contractual Life (Years)		3 years 11 months
Exercisable, Aggregate Intrinsic Value		$111.40

Common_Equity_Details_2

Common Equity (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014
Stock options outstanding
Options Outstanding, Number, Total	6,770,194
Options Outstanding, Weighted-Average Exercise Price	$29.99
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	5 years 8 months
Options Exercisable, Number, Total	3,890,339
Options Exercisable, Weighted-Average Exercise Price	$24.10
Options Exercisable, Weighted-Average Remaining Contractual Life (Years)	3 years 11 months
Exercise Price, Range One [Member]
Stock options outstanding
Options Outstanding, Number, Total	1,498,071
Options Outstanding, Weighted-Average Exercise Price	$20.86
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	3 years 6 months
Options Exercisable, Number, Total	1,498,071
Options Exercisable, Weighted-Average Exercise Price	$20.86
Options Exercisable, Weighted-Average Remaining Contractual Life (Years)	3 years 6 months
Exercise Price, Range One [Member] | Maximum [Member]
Stock options outstanding
Options Outstanding, Weighted-Average Exercise Price	$21.11
Exercise Price, Range One [Member] | Minimum [Member]
Stock options outstanding
Options Outstanding, Weighted-Average Exercise Price	$17.10
Exercise Price, Range Two [Member]
Stock options outstanding
Options Outstanding, Number, Total	2,153,513
Options Outstanding, Weighted-Average Exercise Price	$25.06
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	3 years 8 months
Options Exercisable, Number, Total	2,153,513
Options Exercisable, Weighted-Average Exercise Price	$25.06
Options Exercisable, Weighted-Average Remaining Contractual Life (Years)	3 years 8 months
Exercise Price, Range Two [Member] | Maximum [Member]
Stock options outstanding
Options Outstanding, Weighted-Average Exercise Price	$29.35
Exercise Price, Range Two [Member] | Minimum [Member]
Stock options outstanding
Options Outstanding, Weighted-Average Exercise Price	$23.88
Exercise Price, Range Three [Member]
Stock options outstanding
Options Outstanding, Number, Total	3,118,610
Options Outstanding, Weighted-Average Exercise Price	$37.79
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	8 years 0 months
Options Exercisable, Number, Total	238,755
Options Exercisable, Weighted-Average Exercise Price	$35.88
Options Exercisable, Weighted-Average Remaining Contractual Life (Years)	7 years 5 months
Exercise Price, Range Three [Member] | Maximum [Member]
Stock options outstanding
Options Outstanding, Weighted-Average Exercise Price	$41.03
Exercise Price, Range Three [Member] | Minimum [Member]
Stock options outstanding
Options Outstanding, Weighted-Average Exercise Price	$34.88

Common_Equity_Details_3

Common Equity (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Non-vested options
Granted, Weighted-Average Exercise Price	$4.18	$3.45	$3.34
Outstanding, Shares, Ending Balance	6,770,194
Outstanding, Weighted-Average Exercise Price, Ending	$29.99
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, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$3.38
Non-vested options
Outstanding, Shares, Beginning Balance	2,380,790
Granted, shares	899,500
Granted, Weighted-Average Exercise Price	$4.18
Vested, shares	-383,240
Vested, Weighted-Average Exercise Price	$3.26
Forfeited, shares	-17,195
Forfeited, Weighted-Average Exercise Price	$3.56
Outstanding, Shares, Ending Balance	2,879,855
Outstanding, Weighted-Average Exercise Price, Ending	$3.65

Common_Equity_Details_4

Common Equity (Details 4) (USD $)	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Repurchased During Period, Shares			2,700,000	5,400,000	4,300,000
Common Equity (Textuals)
Common stock shares, Authorized			325,000,000	325,000,000
Common stock shares, Outstanding			225,517,339	225,962,959
Exercise price of non qualified stock options	$52.90
Intrinsic value of options exercised			$50,500,000	$44,500,000	$47,500,000
Exercise price of the stock option on the grant date		no less than 100% of the common stock's fair market value
Minimum percentage award based on performance unit			0
Maximum percentage award based on performance unit			1.75
Amount paid for Shares Purchased by agents from open market			123,200,000	223,400,000	153,200,000
Exercise of stock options			50,300,000	48,500,000	49,800,000
Maximum period to defer interest payments on the Junior Notes			We have the option to defer interest payments on the Junior Notes, from time to time, for one or more periods of up to 10 consecutive years per period. During any period in which we defer interest payments, we may not declare or pay any dividends or distributions on, or redeem, repurchase or acquire, our common stock.
Ability to declare common dividends limited to Percentage of Net Income by Wisconsin Electric			limited to 75% or 50%
Wisconsin Electric's common stock equity to total capitalization			is less than 25% and 20%
3.60% Serial Preferred Stock			3.60%
Maximum percentage of equity method investment			50.00%
Equity method investment			3,700,000,000
Percentage of equity method investment exceeding consolidated net assets			25.00%
Stock Repurchased During Period, Value			123,200,000	223,400,000	153,200,000
Share Repurchase Plan, 2014 - 2017 [Member] [Domain]
Common Equity (Textuals)
Stock Repurchase Program, Authorized Amount				300,000,000
Share Repurchase Plan, 2011 [Member]
Common Equity (Textuals)
Treasury Stock Acquired, Average Cost Per Share			$43.66
Treasury Stock, Value, Acquired, Cost Method			18,600,000
Share Repurchases to Fulfill Exercised Stock Options and Restricted Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Repurchased During Period, Shares			2,300,000	2,400,000	2,800,000
Common Equity (Textuals)
Stock Repurchased During Period, Value			104,600,000	97,400,000	101,400,000
Share Repurchase Plan, 2011 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Repurchased During Period, Shares			400,000	3,000,000	1,500,000
Common Equity (Textuals)
Stock Repurchased During Period, Value			$18,600,000	$126,000,000	$51,800,000
Stock Options [Member]
Common Equity (Textuals)
Stock options awarded under long-term incentive compensation			899,500
Mimimum period after grant that stock options can be exercised		6 months
Expiration of options from time of grant		10 years

Preferred_Stock_Details

Preferred Stock (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Preferred Stock, Value, Issued	$30.40	$30.40
Six Per Cent. Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	45,000
Preferred Stock, Shares Outstanding	44,498
Preferred Stock, Redemption Price Per Share	$0
Preferred Stock, Value, Issued	4.4
Serial preferred stock, $100 par value; authorized 2,286,500 shares [Member] [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	2,286,500
Serial preferred stock, 3.60% Series Redeemable [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	260,000
Preferred Stock, Redemption Price Per Share	$101
Preferred Stock, Value, Issued	26
Serial preferred stock, $25 par value; authorized 5,000,000 shares; none outstanding [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	5,000,000
Preferred Stock, Shares Outstanding	0
Preferred Stock, Redemption Price Per Share	$0
Preferred Stock, Value, Issued	0
Wisconsin Electric [Member]
Class of Stock [Line Items]
Preferred Stock, Value, Issued	30.4	30.4
Wisconsin Electric [Member] | Six Per Cent. Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized		45,000
Preferred Stock, Dividend Rate, Percentage	6.00%	6.00%
Preferred Stock, Par or Stated Value Per Share	$100	$100
Preferred Stock, Shares Outstanding		44,498
Preferred Stock, Redemption Price Per Share		$0
Preferred Stock, Value, Issued		4.4
Wisconsin Electric [Member] | Serial preferred stock, $100 par value; authorized 2,286,500 shares [Member] [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized		2,286,500
Preferred Stock, Par or Stated Value Per Share	$100	$100
Wisconsin Electric [Member] | Serial preferred stock, 3.60% Series Redeemable [Member]
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage	3.60%	3.60%
Preferred Stock, Par or Stated Value Per Share	$100	$100
Preferred Stock, Shares Outstanding		260,000
Preferred Stock, Redemption Price Per Share		$101
Preferred Stock, Value, Issued		26
Wisconsin Electric [Member] | Serial preferred stock, $25 par value; authorized 5,000,000 shares; none outstanding [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized		5,000,000
Preferred Stock, Par or Stated Value Per Share	$25	$25
Preferred Stock, Shares Outstanding		0
Preferred Stock, Redemption Price Per Share		$0
Preferred Stock, Value, Issued		0
Wisconsin Energy Corporation [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	15,000,000	15,000,000
Preferred Stock, Par or Stated Value Per Share	$0.01	$0.01
Preferred Stock, Shares Outstanding	0	0
Preferred Stock, Redemption Price Per Share	$0	$0
Preferred Stock, Value, Issued	$0	$0

LongTerm_Debt_and_Capital_Leas2

Long-Term Debt and Capital Lease Obligations (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2009
	Megawatt
Long-term debt outstanding maturities and sinking fund requirements
Next year	$399.50
Year 2	27.4
Year 3	29.5
Year 4	281.1
Year 5	282.7
Thereafter	3,532.20
Total	4,552.40
Summary of capitalized leased facilities
Long-term power purchase commitment	140.3	140.3
Accumulated amortization	-98.3	-92.5
Total Leased Facilities	42	47.8
Future minimum lease payments under capital lease and present value of net minimum lease payments
Due next year	43.5
Due in two years	45.1
Due in three years	13.9
Due in four years	14.7
Due in five years	15.5
Thereafter	41.3
Total Minimum Lease Payments	174
Less: Estimated Executory Costs	-54.7
Capital Leases Future Minimum Payments Due, Less Executory Costs	119.3
Less: Interest	-34.8
Net Minimum Lease Payments	84.5
Less: Due Currently	-24.6
Future minimum lease payments under our capital lease and the present value of our net minimum lease payments	59.9
Long-Term Debt and Capital Lease Obligations (Textuals) [Abstract]
Number of series of tax-exempt pollution control refunding bonds	2
Restriction under RCC	The RCC provides that we may not redeem, defease or purchase and our subsidiaries may not purchase any Junior Notes on or before May 15, 2037, unless, subject to certain limitations described in the RCC, during the 180 days prior to the date of redemption, defeasance or purchase, we have received a specified amount of proceeds from the sale of qualifying securities.
Period of Power purchase contract with an unaffiliated independent power producer	25 years
Power capacity from a gas-fired cogeneration facility under capital lease (MW)	236
Minimum energy requirement in gas-fired cogeneration facility	0
Power purchase contract expiration year	31-Dec-22
Power purchase contract expected future renewable period	10 years
Total operating lease payment	34.9	33.7
Increase in regulatory asset due to minimum lease payment			78.5
Regulatory asset value at the end of life of contract	0
Total capital lease obligation	84.5	104.3
Capital lease obligation at the end of life of contract	0
Notes (secured, nonrecourse), 6.09% due 2030-2040 [Member]
Long-Term Debt and Capital Lease Obligations (Textuals) [Abstract]
Debt instrument interest rate stated percentage rate	6.09%	6.09%
Notes (unsecured), 6.20% due 2033 [Member]
Long-Term Debt and Capital Lease Obligations (Textuals) [Abstract]
Unsecured Long-term Debt, Noncurrent	200	200
Debt instrument interest rate stated percentage rate	6.20%	6.20%
Junior Notes (unsecured), 6.25% due 2067 [Member]
Long-Term Debt and Capital Lease Obligations (Textuals) [Abstract]
Unsecured Long-term Debt, Noncurrent	500	500
Interest Rate effective May 2017 for Junior Notes	the three-month LIBOR Rate plus 211.25 basis points and will reset quarterly
Debt instrument interest rate stated percentage rate	6.25%	6.25%
Parent Company [Member]
Long-term debt outstanding maturities and sinking fund requirements
Next year	0
Year 2	0
Year 3	0
Year 4	0
Year 5	0
Thereafter	700
Total	700
Wisconsin Electric [Member]
Long-Term Debt and Capital Lease Obligations (Textuals) [Abstract]
Unsecured Long-term Debt, Noncurrent	$147

ShortTerm_Debt_Details

Short-Term Debt (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Short-Term Debt (Textuals) [Abstract]
Undrawn lines under bank back-up credit facilities	$1,200,000,000
Short-term debt outstanding supported by the available lines of credit	617,600,000
Wisconsin Energy Corporation [Member]
Short-Term Debt (Textuals) [Abstract]
Minimum total funded debt to capitalization ratio	70.00%
Wisconsin Electric [Member]
Short-Term Debt (Textuals) [Abstract]
Minimum total funded debt to capitalization ratio	65.00%
Wisconsin Gas [Member]
Short-Term Debt (Textuals) [Abstract]
Minimum total funded debt to capitalization ratio	65.00%
Commercial Paper [Member]
Short-term notes payable balances and their corresponding weighted-average interest rates
Commercial paper, balance	617,600,000	537,400,000
Commercial paper, weighted-average interest rate	0.22%	0.20%
Commercial paper [Abstract]
Maximum Short-Term Debt Outstanding	721,400,000	594,500,000
Average Short-Term Debt Outstanding	$468,100,000	$359,100,000
Weighted-Average Interest Rate	0.18%	0.25%

Derivative_Instruments_Details

Derivative Instruments (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivatives Fair Value [Line Items]
Derivative, Asset	$15.30	$11.80
Derivative, Liability	12.5	0.3
Gains (losses)	20.5	6.9
Other Deferred Charges and Other Assets [Member]
Derivatives Fair Value [Line Items]
Long-term portion of derivative assets	0.6
Other Long-Term Liabilities [Member]
Derivatives Fair Value [Line Items]
Long-term portion of derivative liabilities	0.8
Natural Gas [Member]
Derivatives Fair Value [Line Items]
Derivative, Asset	5	5.6
Derivative, Liability	12.3	0.1
Volume	40.5 million Dth	48.6 million Dth
Gains (losses)	7.3	-8.5
Fuel Oil [Member]
Derivatives Fair Value [Line Items]
Derivative, Asset	0	0.6
Derivative, Liability	0	0
Volume	9.2 million gallons	8.6 million gallons
Gains (losses)	0.5	0.5
FTRs [Member]
Derivatives Fair Value [Line Items]
Derivative, Asset	7	3.5
Derivative, Liability	0	0
Volume	26.1 million MWh	25.3 million MWh
Gains (losses)	12.7	14.9
Coal [Member]
Derivatives Fair Value [Line Items]
Derivative, Asset	3.3	2.1
Derivative, Liability	$0.20	$0.20

Derivative_Instruments_Details1

Derivative Instruments (Details 1) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Regulatory Assets [Line Items]
Regulatory assets related to derivatives	$1,271.20	$1,108.50
Derivative [Member]
Regulatory Assets [Line Items]
Regulatory assets related to derivatives	$14.70	$0.30

Derivative_Instruments_Details2

Derivative Instruments (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Regulatory Liabilities [Line Items]
Regulatory liabilities related to derivatives	$830.60	$879.10
Derivative [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities related to derivatives	$14.20	$9.60

Derivative_Instruments_Details3

Derivative Instruments (Details 3) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Collateral in margin accounts	$11.20	$0
Derivative Asset	15.3	11.8
Derivative Liability	12.5	0.3
Reclassification in treasury lock agreement settlement payments deferred in Accumulated Other Comprehensive Income as increase to interest Expense	241.5	252.1	248.2
Derviative Instrument by Counterparty, Gross Amount Recognized on Balance Sheet [Member]
Derivative [Line Items]
Derivative Asset	15.3	11.8
Derivative Liability	12.5	0.3
Derviative Instrument by Counterparty, Gross Amount Not Offset on Balance Sheet [Member] [Member]
Derivative [Line Items]
Collateral in margin accounts	10.3	0
Derivative Asset	-0.4	0
Derivative Liability	-11.5	0
Derviative Instrument by Counterparty, Net Amount [Member]
Derivative [Line Items]
Derivative Asset	14.9	11.8
Derivative Liability	$1	$0.30

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Assets:
Derivative, Asset	$15.30	$11.80
Total	15.3	11.8
Liabilities:
Derivative, Liability	12.5	0.3
Total	12.5	0.3
Fair Value, Inputs, Level 1 [Member]
Assets:
Derivative, Asset	1.1	5.7
Total	1.1	5.7
Liabilities:
Derivative, Liability	11.5	0
Total	11.5	0
Fair Value, Inputs, Level 2 [Member]
Assets:
Derivative, Asset	7.2	2.6
Total	7.2	2.6
Liabilities:
Derivative, Liability	1	0.3
Total	1	0.3
Fair Value, Inputs, Level 3 [Member]
Assets:
Derivative, Asset	7	3.5
Total	7	3.5
Liabilities:
Derivative, Liability	0	0
Total	$0	$0

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 1) (Derivative [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative [Member]
Fair value of derivatives classified as Level 3 in the fair value hierarchy
Beginning Balance	$3.50	$4.70
Realized and unrealized gains (losses)	0	0
Purchases	15.6	10.6
Issuances	0	0
Settlements	-12.1	-11.8
Transfers in and/or out of Level 3	0	0
Ending Balance	$7	$3.50

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial Instruments
Preferred Stock	$30.40	$30.40
Long-term debt including current portion, carrying value	4,552.40	4,626.70
Long-term debt including current portion, fair value	5,126	4,911.80
Fair Value [Member]
Financial Instruments
Preferred Stock	27.1	26
Carrying Amount [Member]
Financial Instruments
Preferred Stock	$30.40	$30.40

Benefits_Details

Benefits (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
New 401k Contribution for new hires				6.00%
Pension Plans [Member]
Change in Benefit Obligation
Benefit Obligation at January 1	$1,410.20	$1,508.50
Service cost	10.1	14.6	21.7
Interest cost	68.1	60.4	65.5
Participants' contributions	0	0
Plan amendments	0	-1
Actuarial loss (gain)	120.4	-81.9
Gross benefits paid	-103.3	-90.4
Benefit Obligation at December 31	1,505.50	1,410.20	1,508.50
OPEB [Member]
Change in Benefit Obligation
Benefit Obligation at January 1	362.7	381.2
Service cost	8.5	10	10.3
Interest cost	17.8	15.6	20.3
Participants' contributions	9.1	8.9
Plan amendments	-4.6	0
Actuarial loss (gain)	29.4	-27.7
Gross benefits paid	-26.4	-26.3
Federal subsidy on benefits paid	1.2	1
Benefit Obligation at December 31	$397.70	$362.70	$381.20

Benefits_Details_1

Benefits (Details 1) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2015	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Current pension plan asset allocation in equity investments	45.00%				35.00%
Current pension plan asset allocation in fixed income investments	55.00%				55.00%
Current pension plan asset allocation in real estate investments					10.00%
Amounts recognized in Consolidated Balance Sheets
Other long-term liabilities	$203,800,000	$173,200,000
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	1,504,600,000	1,409,500,000
Defined Benefit Plan, Benefit Obligation	1,505,500,000	1,410,200,000	1,508,500,000
Change in Plan Assets
Fair Value at January 1	1,451,000,000	1,385,400,000
Actual earnings (loss) on plan assets	88,500,000	147,300,000
Employer contributions	8,400,000	8,700,000
Participants' contributions	0	0
Gross benefits paid	-103,300,000	-90,400,000
Fair Value at December 31	1,444,600,000	1,451,000,000
Amounts recognized in Consolidated Balance Sheets
Other deferred charges	39,200,000	138,700,000
Other long-term liabilities	100,100,000	97,900,000
Net Liability	60,900,000	-40,800,000
Amounts not yet been recognized in net periodic benefit cost
Net actuarial loss	622,700,000	528,800,000
Prior service costs (credits)	6,800,000	8,800,000
Total	629,500,000	537,600,000
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	397,700,000	362,700,000	381,200,000
Change in Plan Assets
Fair Value at January 1	327,600,000	285,400,000
Actual earnings (loss) on plan assets	17,700,000	45,500,000
Employer contributions	5,500,000	14,100,000	17,700,000
Participants' contributions	9,100,000	8,900,000
Gross benefits paid	-26,400,000	-26,300,000
Fair Value at December 31	333,500,000	327,600,000	285,400,000
Amounts recognized in Consolidated Balance Sheets
Other deferred charges	39,500,000	40,200,000
Other long-term liabilities	103,700,000	75,300,000
Net Liability	64,200,000	35,100,000
Amounts not yet been recognized in net periodic benefit cost
Net actuarial loss	44,100,000	9,800,000
Prior service costs (credits)	-4,600,000	-1,700,000
Total	39,500,000	8,100,000
Pension, Qualified [Member] | Pension Plans [Member]
Change in Plan Assets
Employer contributions	$0	$0	$95,600,000	$100,000,000

Benefits_Details_2

Benefits (Details 2) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2015	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Matching contributions under Savings Plans	$14,200,000	$14,200,000	$13,800,000
A one-percentage-point change in assumed health care cost trend rates effects
1% Increase, in assumed health care cost trend rates, Effect on, Post-retirement benefit obligation	30,200,000
1% Decrease, in assumed health care cost trend rates, Effect on, Post-retirement benefit obligation	-25,400,000
1% Increase, in assumed health care cost trend rates, Effect on, Total of service and interest cost components	3,100,000
1% Decrease, in assumed health care cost trend rates, Effect on, Total of service and interest cost components	-2,500,000
Benefits (Textuals) [Abstract]
Health care cost trend rate up to specified age	65
Health care cost trend rate post specified age	65
Current pension plan target asset allocation in equity investments	45.00%				35.00%
Current pension plan target asset allocation in fixed income investments	55.00%				55.00%
Other Post-Retirement Employee Benefits target asset allocation in equity investments					60.00%
Other Post-Retirement Employee Benefits target asset allocation in fixed income investments					40.00%
Matching contributions under Savings Plans	14,200,000	14,200,000	13,800,000
Postemployment benefits liability	3,300,000	4,200,000
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	1,505,500,000	1,410,200,000	1,508,500,000
Defined Benefit Plan, Amortization of Previously Unrecognized Benefit Costs	48,300,000
Net Periodic Benefit Cost
Service cost	10,100,000	14,600,000	21,700,000
Interest cost	68,100,000	60,400,000	65,500,000
Expected return on plan assets	-98,600,000	-95,800,000	-89,600,000
Amortization of:
Transition obligation	0	0	0
Prior service cost (credit)	2,100,000	2,300,000	2,200,000
Actuarial loss	36,700,000	54,500,000	41,000,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	2,500,000	0
Curtailment (gain)	0	0	400,000
Net Periodic Benefit Cost	18,400,000	38,500,000	41,200,000
Weighted-Average assumptions used to determine benefit obligations as of Dec. 31
Discount rate	4.15%	5.00%	4.10%
Rate of compensation increase	4.00%	4.00%	4.00%
Weighted-Average assumptions used to determine net cost for year ended Dec. 31
Discount rate	5.00%	4.10%	5.05%
Expected return on plan assets	7.25%	7.25%	7.25%
Rate of compensation increase	4.00%	4.00%	4.00%
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	1,444,600,000	1,451,000,000	1,385,400,000
Employer contributions to defined benefit plan
Employer contributions	8,400,000	8,700,000
Expected benefit payments in future
2012	104,700,000
2013	103,600,000
2014	104,300,000
2015	102,300,000
2016	102,400,000
2017-2021	491,800,000
Pension Plans [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	760,600,000	873,200,000
Pension Plans [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	672,400,000	577,800,000
Pension Plans [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	11,600,000	0
Pension Plans [Member] | Cash And Cash Equivalents [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	6,400,000	21,000,000
Pension Plans [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	6,400,000	21,000,000
Pension Plans [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | U.S. Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	503,800,000	519,500,000
Pension Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	503,800,000	519,500,000
Pension Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | International Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	158,400,000	181,900,000
Pension Plans [Member] | International Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	128,600,000	146,200,000
Pension Plans [Member] | International Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	29,800,000	35,700,000
Pension Plans [Member] | International Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | U.S. Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	641,800,000	613,600,000
Pension Plans [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	42,500,000	108,400,000
Pension Plans [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	599,300,000	505,200,000
Pension Plans [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | International Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	122,600,000	115,000,000
Pension Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	79,300,000	78,100,000
Pension Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	43,300,000	36,900,000
Pension Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
Pension Plans [Member] | Private Placement [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	11,600,000
Pension Plans [Member] | Private Placement [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0
Pension Plans [Member] | Private Placement [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0
Pension Plans [Member] | Private Placement [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	11,600,000
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	397,700,000	362,700,000	381,200,000
Defined Benefit Plan, Amortization of Previously Unrecognized Benefit Costs	900,000
Net Periodic Benefit Cost
Service cost	8,500,000	10,000,000	10,300,000
Interest cost	17,800,000	15,600,000	20,300,000
Expected return on plan assets	-23,700,000	-21,300,000	-19,000,000
Amortization of:
Transition obligation	0	0	300,000
Prior service cost (credit)	-1,800,000	-2,000,000	-1,900,000
Actuarial loss	1,200,000	3,700,000	7,300,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	0	0
Curtailment (gain)	0	0	0
Net Periodic Benefit Cost	2,000,000	6,000,000	17,300,000
Weighted-Average assumptions used to determine benefit obligations as of Dec. 31
Discount rate	4.20%	4.95%	4.15%
Weighted-Average assumptions used to determine net cost for year ended Dec. 31
Discount rate	4.95%	4.15%	5.20%
Expected return on plan assets	7.50%	7.50%	7.50%
Assumed health care cost trend rates as of Dec. 31
Health care cost trend rate assumed for next year, Pre 65	0.075	0.075	0.075
Health care cost trend rate assumed for next year, Post 65	0.075	0.075	0.075
Rate that the cost trend rate gradually adjusts to	0.05	0.05	0.05
Year that the rate reaches the rate it is assumed to remain at (Pre 65 / Post 65)	2021/2021	2021/2021	2017/2017
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	333,500,000	327,600,000	285,400,000
Employer contributions to defined benefit plan
Employer contributions	5,500,000	14,100,000	17,700,000
Expected benefit payments in future
2012	25,500,000
2013	22,300,000
2014	22,800,000
2015	23,300,000
2016	24,100,000
2017-2021	122,500,000
OPEB [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	210,600,000	222,700,000
OPEB [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	121,900,000	104,900,000
OPEB [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	1,000,000	0
OPEB [Member] | Cash And Cash Equivalents [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	1,400,000	2,600,000
OPEB [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	1,400,000	2,600,000
OPEB [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | U.S. Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	146,000,000	148,000,000
OPEB [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	146,000,000	148,000,000
OPEB [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | International Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	44,700,000	49,700,000
OPEB [Member] | International Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	42,200,000	46,900,000
OPEB [Member] | International Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	2,500,000	2,800,000
OPEB [Member] | International Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | U.S. Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	115,900,000	104,700,000
OPEB [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	3,500,000	8,400,000
OPEB [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	112,400,000	96,300,000
OPEB [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | International Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	24,500,000	22,600,000
OPEB [Member] | International Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	17,500,000	16,800,000
OPEB [Member] | International Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	7,000,000	5,800,000
OPEB [Member] | International Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0	0
OPEB [Member] | Private Placement [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	1,000,000
OPEB [Member] | Private Placement [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0
OPEB [Member] | Private Placement [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	0
OPEB [Member] | Private Placement [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets	1,000,000
Pension, Qualified [Member] | Pension Plans [Member]
Employer contributions to defined benefit plan
Employer contributions	0	0	95,600,000	100,000,000
Pension, Non-Qualified [Member] | Pension Plans [Member]
Employer contributions to defined benefit plan
Employer contributions	$8,400,000	$8,700,000	$7,100,000

Segment_Reporting_Details

Segment Reporting (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financial information of reportable operating segments
Operating Revenues	$4,997.10	[1]	$4,519	[1]	$4,246.40	[1]
Depreciation and Amortization	408.8		388.1		364.2
Operating Income (Loss)	1,112.10		1,080.10		1,000.30
Equity in Earnings of Unconsolidated Affiliates	65.9		68.4		65.5
Interest Expense, net	241.5		252.1		248.2
Income Tax Expense (Benefit)	361.7		337.9		306.3
Net Income (Loss)	588.3		577.4		546.3
Capital Expenditures	736.1		687.4		707
Total Assets	15,163.40	[2]	14,769.40	[2]	14,285	[2]
Utility Energy [Member]
Financial information of reportable operating segments
Operating Revenues	4,941.30	[1]	4,462	[1]	4,190.80	[1]
Depreciation and Amortization	340.6		320.2		296.4
Operating Income (Loss)	770.2		719.4		647.7
Equity in Earnings of Unconsolidated Affiliates	66		68.5		65.7
Interest Expense, net	128.8		136.2		129.4
Income Tax Expense (Benefit)	268.9		243.6		214.9
Net Income (Loss)	447.2		425.1		400.6
Capital Expenditures	689.9		657.9		697.3
Total Assets	14,912.80	[2]	14,460.40	[2]	13,988.10	[2]
Non-Utility Energy [Member]
Financial information of reportable operating segments
Operating Revenues	447.1	[1]	446.7	[1]	439.9	[1]
Depreciation and Amortization	67.5		67.1		67.1
Operating Income (Loss)	368.2		367.1		358.8
Equity in Earnings of Unconsolidated Affiliates	0		0		0
Interest Expense, net	64.6		65.7		66.7
Income Tax Expense (Benefit)	121.4		120.2		116.6
Net Income (Loss)	182.8		181.6		175.9
Capital Expenditures	41.1		26.1		5.5
Total Assets	2,821.80	[2]	2,846.50	[2]	2,903.50	[2]
Corporate and Other [Member]
Financial information of reportable operating segments
Operating Revenues	1.3	[1],[3]	1.3	[1],[3]	1.2	[1],[3]
Depreciation and Amortization	0.7	[3]	0.8	[3]	0.7	[3]
Operating Income (Loss)	-26.3	[3]	-6.4	[3]	-6.2	[3]
Equity in Earnings of Unconsolidated Affiliates	-0.1	[3]	-0.1	[3]	-0.2	[3]
Interest Expense, net	48.8	[3]	50.8	[3]	52.5	[3]
Income Tax Expense (Benefit)	-28.6	[3]	-25.9	[3]	-25.2	[3]
Net Income (Loss)	588	[3]	577.2	[3]	546.1	[3]
Capital Expenditures	5.1	[3]	3.4	[3]	4.2	[3]
Total Assets	4,880.30	[2],[3]	4,719.50	[2],[3]	4,431.40	[2],[3]
Reconciling Items [Member]
Financial information of reportable operating segments
Operating Revenues	-392.6	[1]	-391	[1]	-385.5	[1]
Depreciation and Amortization	0		0		0
Operating Income (Loss)	0		0		0
Equity in Earnings of Unconsolidated Affiliates	0		0		0
Interest Expense, net	-0.7		-0.6		-0.4
Income Tax Expense (Benefit)	0		0		0
Net Income (Loss)	-629.7		-606.5		-576.3
Capital Expenditures	0		0		0
Total Assets	-7,451.50	[2]	-7,257	[2]	-7,038	[2]
Elimination [Member]
Financial information of reportable operating segments
Total Assets	($2,172.90)		($2,231.20)		($2,286.70)
[1]	An elimination for intersegment revenues is included in Operating Revenues. This elimination is primarily between We Power and Wisconsin Electric.
[2]	An elimination of $2,172.9 million, $2,231.2 million and $2,286.7 million is included in Total Assets as of December 31, 2014, 2013 and 2012, respectively, for all PTF-related activity between We Power and Wisconsin Electric.
[3]	Corporate & Other includes all other non-utility activities, primarily non-utility real estate investment and development by Wispark as well as interest on corporate debt.

Related_Parties_Details

Related Parties (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Income (Loss) from Equity Method Investments	$65.90	$68.40	$65.50
American Transmission Company [Member]
Provided and received services from the associated companies
Services Received, -ATC	231.4	234.2	222.7
Receivable and payable balances with ATC
Services Received, -ATC	19.3	19.5
Related Parties (Textuals) [Abstract]
Equity interest in ATC	26.20%
Services [Member] | American Transmission Company [Member]
Provided and received services from the associated companies
Services Provided, -ATC	8.1	9	8.2
Receivable and payable balances with ATC
Services Provided, -ATC	0.6	0.6
Transmission Affiliate [Member]
Related Party Transaction [Line Items]
Income (Loss) from Equity Method Investments	66	68.5	65.7
Distributions from transmission affiliate	$57.50	$54.50	$52.60

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Future minimum payments for the next five years and thereafter for our operating lease contracts
2014	$5.20
2015	3.9
2016	3.2
2017	3.1
2018	1.2
Thereafter	21.5
Total	38.1
Manufactured Gas Plant Sites [Member]
Commitment and Contingencies (Textuals) [Abstract]
Reserves related to future remediation costs	32.6	36.9
Commitments and Contingencies (Textuals) [Abstract]
Estimated future detailed site investigation and remediation costs, minimum	15
Estimated Future detailed site investigation and remediation costs, maximum	47
Period for future costs of detailed site investigation and remediation costs	over the next ten years
Period to recover remediation cost of manufactured gas plant sites	5 years
Coal combustion product landfill sites [Member]
Commitment and Contingencies (Textuals) [Abstract]
Expense related to environmental remediation	0.1	0.1	0.3
Reserves related to landfill sites	0
Commitments and Contingencies (Textuals) [Abstract]
Expense related to environmental remediation	$0.10	$0.10	$0.30

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Cash Flow Information (Textuals)
Interest paid, net of amounts capitalized	$241.10	$250.40	$241.20
Income Taxes Paid, Net	22
Net refunds from income taxes		39.6	107
Accounts payable related to capital expenditures	1.8	4.7	15.7
Deferred Revenue, Revenue Recognized	$55.70	$56.50	$54.90

Subsequent_Event_Details

Subsequent Event (Details) (Subsequent Event [Member], USD $)	Jan. 12, 2015
In Millions, unless otherwise specified
Subsequent Event [Member]
Subsequent Event [Line Items]
Carrying value of Michigan assets to be sold	$292
Unrecovered plant costs to be sought from customers	$190

Condensed_Parent_Company_Finan

Condensed Parent Company Financial Statements (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Parent Company Income Statement
Other Income, Net	$13.40	$18.80	$34.80
Interest Expense, net	241.5	252.1	248.2
Income (Loss) from Continuing Operations Before Income Taxes	950	915.3	852.6
Income Tax Benefit	-361.7	-337.9	-306.3
Net Income	588.3	577.4	546.3
Subsidiaries [Member]
Condensed Parent Company Income Statement
Income from Continuing Operations	635	607.8	577.6
Wisconsin Energy Corporation [Member]
Condensed Parent Company Income Statement
Other Income, Net	2.8	3.1	3.2
Corporate Expense	26.8	5.5	4.8
Interest Expense, net	53.1	54.4	55.7
Income (Loss) from Continuing Operations Before Income Taxes	-77.1	-56.8	-57.3
Income Tax Benefit	30.4	26.4	26
Income from Continuing Operations	-46.7	-30.4	-31.3
Net Income	$588.30	$577.40	$546.30

Condensed_Parent_Company_Finan1

Condensed Parent Company Financial Statements (Details 1) (USD $)	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
In Millions, unless otherwise specified
Current Assets
Cash and cash equivalents	$61.90		$26		$35.60		$14.10
Prepaid taxes and other	148.2		145.7
Total Current Assets	1,535.40		1,551.10
Property and Investments
Investment in subsidiary companies	424.1		402.7
Other	200.3		322.5
Total Deferred Charges and Other Assets	1,913.40		1,872.90
Total Assets	15,163.40	[1]	14,769.40	[1]	14,285	[1]
Current Liabilities
Short-term debt	617.6		537.4
Other	168.6		177.3
Total Current Liabilities	1,668.70		1,496.40
Long-term debt	4,186.40		4,363.20
Other Long-term liabilities	303		295.9
Stockholder's equity	4,419.70		4,233		4,135.10		3,963.30
Total Capitalization and Liabilities	15,163.40		14,769.40
Wisconsin Energy Corporation [Member]
Current Assets
Cash and cash equivalents	37.3		0.3		0.9		0.5
Accounts and notes receivable from associated companies	37.8		37.4
Prepaid taxes and other	264.2		297.6
Total Current Assets	339.3		335.3
Property and Investments
Investment in subsidiary companies	4,917.80		4,761.80
Other	1.5		1.8
Total Property and Investments	4,919.30		4,763.60
Total Deferred Charges and Other Assets	118.7		143.2
Total Assets	5,377.30		5,242.10
Current Liabilities
Short-term debt	0		72
Notes payable due associated companies	117.2		113.8
Other	22.4		11.8
Total Current Liabilities	139.6		197.6
Long-term debt	695.8		695
Other Long-term liabilities	122.2		116.5
Stockholder's equity	4,419.70		4,233
Total Capitalization and Liabilities	$5,377.30		$5,242.10
[1]	An elimination of $2,172.9 million, $2,231.2 million and $2,286.7 million is included in Total Assets as of December 31, 2014, 2013 and 2012, respectively, for all PTF-related activity between We Power and Wisconsin Electric.

Condensed_Parent_Company_Finan2

Condensed Parent Company Financial Statements (Details 2) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities
Net income	$588.30	$577.40	$546.30
Reconciliation to cash
Deferred income taxes, net	329.2	313.8	294.4
Accrued income taxes, net	-11.4	36.6	116.9
Other current assets	-13.9	2.8	12.1
Other current liabilities	-18.8	7.2	-14.9
Accounts receivable and accrued revenues	80.7	-162.9	38.3
Other, net	-112.1	49.2	-164
Cash Provided by Operating Activities	1,197.70	1,231	1,173.90
Investing Activities
Proceeds from asset sales	13.9	2.5	8.7
Capital contributions to associated companies	-13.1	-10.5	-15.7
Cash Used in Investing Activities	-756.8	-745.8	-729.6
Financing Activities
Exercise of stock options	50.3	48.5	49.8
Purchase of common stock	-123.2	-223.4	-153.2
Dividends paid on common stock	-352	-328.9	-276.3
Issuance of long-term debt	250	251	251.8
Retirement and repurchase of long-term debt	-324.3	-397.2	-20.3
Change in short-term debt	80.2	142.8	-275.3
Other, net	14	12.4	0.7
Cash Used in Financing Activities	-405	-494.8	-422.8
Change in Cash and Cash Equivalents	35.9	-9.6	21.5
Cash and Cash Equivalents at Beginning of Year	26	35.6	14.1
Cash and Cash Equivalents at End of Year	61.9	26	35.6
Wisconsin Energy Corporation [Member]
Operating Activities
Net income	588.3	577.4	546.3
Reconciliation to cash
Equity in susidiaries' earnings	-635	-607.8	-577.6
Dividends and distributions from subsidiaries	720	720.4	842.3
Deferred income taxes, net	60.1	-7.8	104.4
Accrued income taxes, net	4.1	66.8	-457.9
Other current assets	0	-0.1	0.2
Other current liabilities	5.1	-22.9	-6.7
Accounts receivable and accrued revenues	-0.3	-2.7	22.5
Other, net	-8.1	-21.6	-8.1
Cash Provided by Operating Activities	734.2	701.7	465.4
Investing Activities
Capital contributions to associated companies	-225.5	-195.3	-21.5
Capitalized interest and other	5	4	12.6
Cash Used in Investing Activities	-220.5	-191.3	-8.9
Financing Activities
Exercise of stock options	50.3	48.5	49.8
Purchase of common stock	-123.2	-223.4	-153.9
Dividends paid on common stock	-352	-328.9	-276.3
Change in short-term debt	-72	5	-79.5
Change in notes payable due associated companies	3.5	-26.8	3.8
Other, net	16.7	14.6	0
Cash Used in Financing Activities	-476.7	-511	-456.1
Change in Cash and Cash Equivalents	37	-0.6	0.4
Cash and Cash Equivalents at Beginning of Year	0.3	0.9	0.5
Cash and Cash Equivalents at End of Year	$37.30	$0.30	$0.90

Condensed_Parent_Company_Finan3

Condensed Parent Company Financial Statements (Details 3) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Parent Company long-term debt outstanding
Next year	$399.50
Year 2	27.4
Year 3	29.5
Year 4	281.1
Year 5	282.7
Thereafter	3,532.20
Total	4,552.40
Wisconsin Energy Corporation [Member]
Parent Company long-term debt outstanding
Next year	0
Year 2	0
Year 3	0
Year 4	0
Year 5	0
Thereafter	700
Total	700
Junior Notes (unsecured), 6.25% due 2067 [Member]
Parent Company long-term debt outstanding
Unsecured Long-term Debt, Noncurrent	$500	$500
Interest Rate effective May 2017 for Junior Notes	the three-month LIBOR Rate plus 211.25 basis points and will reset quarterly

Condensed_Parent_Company_Finan4

Condensed Parent Company Financial Statements (Details 5) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Parent Company Financial Statements (Textuals) [Abstract]
Issuance of new notes and the proceeds used to repay short-term debt	$324.30	$397.20	$20.30
Issuance of Junior Notes	250	251	251.8
Restriction under RCC	The RCC provides that we may not redeem, defease or purchase and our subsidiaries may not purchase any Junior Notes on or before May 15, 2037, unless, subject to certain limitations described in the RCC, during the 180 days prior to the date of redemption, defeasance or purchase, we have received a specified amount of proceeds from the sale of qualifying securities.
Interest paid, net of amounts capitalized	241.1	250.4	241.2
Net refunds from income taxes		39.6	107
Wisconsin Energy Corporation [Member]
Condensed Parent Company Financial Statements (Textuals) [Abstract]
Long-term notes outstanding of WECC	50
Minimum Total Funded Debt to Capitalization Ratio, As a Percent	70.00%
Interest paid, net of amounts capitalized	44.4	44.4	45.2
Net refunds from income taxes	95.1	86.1	128.2
Wisconsin Electric and Wisconsin Gas [Member]
Condensed Parent Company Financial Statements (Textuals) [Abstract]
Dividends and distributions from subsidiaries	423
We Power [Member]
Condensed Parent Company Financial Statements (Textuals) [Abstract]
Dividends and distributions from subsidiaries	$297
Notes (unsecured), 6.20% due 2033 [Member]
Condensed Parent Company Financial Statements (Textuals) [Abstract]
Debt instrument interest rate stated percentage rate	6.20%	6.20%
Junior Notes (unsecured), 6.25% due 2067 [Member]
Condensed Parent Company Financial Statements (Textuals) [Abstract]
Debt instrument interest rate stated percentage rate	6.25%	6.25%

Condensed_Parent_Company_Finan5

Condensed Parent Company Financial Statements (Details 6) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial Instruments
Long-term debt including current portion, carrying value	$4,552.40	$4,626.70
Long-term debt including current portion, fair value	5,126	4,911.80
Carrying Amount [Member] | Wisconsin Energy Corporation [Member]
Financial Instruments
Long-term debt including current portion, carrying value	700	700
Fair Value [Member] | Wisconsin Energy Corporation [Member]
Financial Instruments
Long-term debt including current portion, fair value	$770	$749.40

Valuation_and_Qualifying_Accou

Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts
Balance at Beginning of the Period	$61	$58	$61.70
Expense	49.8	49.4	47.7
Deferral	18.4	0.4	-4
Net Write-offs	-54.7	-46.8	-47.4
Balance at End of the Period	$74.50	$61	$58