Long Term Debt (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Wis Elec Debenture due June, 15 2018 [Domain]
Long Term Debt (Textuals)
Issuance of long-term debt	$ 250
Interest rate on long-term debt	1.70%
Wis Elec Debentures due May 15 2013 [Domain]
Long Term Debt (Textuals)
Retirement of long-term debt	$ 300

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant