Condensed Parent Company Financial Statements (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Parent Company long-term debt outstanding
Next year	$ 396.3
Year 2	322.4
Year 3	399.5
Year 4	27.4
Year 5	29.5
Thereafter	3,597.8
Total	4,772.9
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	700.0
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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