Rate Matters (Details) (Public Service Commission of Wisconsin (PSCW) [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
	Dec. 31, 2012	Jun. 30, 2012
2012 Electric and Gas Rate Case - Electric Rates [Member]
Rate Matters [Abstract]
Entity's requested rate increase (decrease)		$ 39.1
Percentage increase in entity's requested rate increase (in hundredths)		6.70%
Entity's requested return on equity (in hundredths)		10.40%
Entity's requested equity ratio percent (in hundredths)		52.50%
Entity's rate base in requested rate increase (decrease)		788.6
Entity's approved rate increase (decrease)	35.5
Percentage increase in entity's approved rate increase (in hundredths)	6.10%
Entity's approved return on equity (in hundredths)	10.40%
Entity's approved equity ratio percent (in hundredths)	52.50%
2012 Electric and Gas Rate Case - Gas Rates [Member]
Rate Matters [Abstract]
Entity's requested rate increase (decrease)		5.3
Percentage increase in entity's requested rate increase (in hundredths)		4.90%
Entity's approved rate increase (decrease)	$ 2.7
Percentage increase in entity's approved rate increase (in hundredths)	2.50%