Condensed Parent Company Financial Statements (Details 4) (Wisconsin Energy Corporation [Member], USD $)	Dec. 31, 2013
Various guarantees to provide financial and performance assurance to third parties on behalf of affiliates
Guarantees, Maximum Potential Future Payments	$ 59,600,000
Guarantees, Outstanding	3,800,000
Liability	0
Letters of Credit [Member]
Various guarantees to provide financial and performance assurance to third parties on behalf of affiliates
Guarantees, Maximum Potential Future Payments	100,000
Guarantees, Outstanding	100,000
Liability	0
Utility Energy [Member]
Various guarantees to provide financial and performance assurance to third parties on behalf of affiliates
Guarantees, Maximum Potential Future Payments	3,800,000
Guarantees, Outstanding	3,800,000
Liability	0
Non-Utility Energy [Member]
Various guarantees to provide financial and performance assurance to third parties on behalf of affiliates
Guarantees, Maximum Potential Future Payments	55,500,000
Guarantees, Outstanding	0
Liability	0
Corporate and Other [Member]
Various guarantees to provide financial and performance assurance to third parties on behalf of affiliates
Guarantees, Maximum Potential Future Payments	300,000
Guarantees, Outstanding	0
Liability	$ 0