Condensed Parent Company Financial Statements (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Parent Company long-term debt outstanding
2012	$ 20.3
2013	396.3
2014	322.4
2015	399.5
2016	27.4
Thereafter	3,375.5
Total	4,541.4
Wisconsin Energy Corporation [Member]
Parent Company long-term debt outstanding
2012	0
2013	0
2014	0
2015	0
2016	0
Thereafter	700.0
Total	$ 700.0

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

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