Preferred Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Preferred Stock, Value, Issued	$ 30.4us-gaap_PreferredStockValue	$ 30.4us-gaap_PreferredStockValue
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	26.0
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	$ 100.00	$ 100.00
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	$ 100.00	$ 100.00
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	$ 100.00	$ 100.00
Preferred Stock, Shares Outstanding		260,000
Preferred Stock, Redemption Price Per Share		$ 101
Preferred Stock, Value, Issued		26.0
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

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The percentage rate used to calculate dividend payments on preferred stock.

+ References

No definition available.

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- Definition

Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

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- Definition

The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (a)

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- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

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- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

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- Definition

Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

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