Rate Matters (Details) (Public Service Commission of Wisconsin (PSCW) [Member], USD $) In Millions, unless otherwise specified	1 Months Ended			0 Months Ended
	May 31, 2013 Electric and Gas Rate Case 2014, Electric Rates [Member]	May 31, 2013 Electric and Gas Rate Case 2014, Gas Rates [Member]	May 31, 2013 Electric and Gas Rate Case 2014 [Member]	Oct. 18, 2013 Subsequent Event [Member] Electric and Gas Rate Case 2014, Electric Rates [Member]	Oct. 04, 2013 Subsequent Event [Member] Electric and Gas Rate Case 2014, Electric Rates [Member]	Oct. 18, 2013 Subsequent Event [Member] Electric and Gas Rate Case 2014, Gas Rates [Member]	Oct. 04, 2013 Subsequent Event [Member] Electric and Gas Rate Case 2014, Gas Rates [Member]	Oct. 18, 2013 Subsequent Event [Member] Electric and Gas Rate Case 2014 [Member]	Oct. 04, 2013 Subsequent Event [Member] Electric and Gas Rate Case 2014 [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount				$ 34.0		$ 0
Public Utilities, Requested Rate Increase (Decrease), Amount	40.0	4.7
Public Utilities, Requested Rate Increase (Decrease), Percentage	6.50%	3.80%
Public Utilities, Requested Return on Equity, Percentage			10.40%					10.40%
Public Utilities, Requested Equity Capital Structure, Percentage			52.50%
Forecasted Average Net Investment Rate Base, Electric Utility			895.3
Forecasted Average Net Investment Rate Base, Natural Gas Utility			89.8
Public Utilities, Return on equity recommended by third parties									10.20%
Public Utilities, Debt capital structure recommended by third parties									52.50%
Public Utilities, Adjustment to requested rate increase (decrease) recommended by third parties related to electric fuel and purchased power					(5.1)		0
Public Utilities, Adjustment to requested rate increase (decrease) recommended by third parties related to the sales forecast					(4.8)		0
Public Utilities, Adjustment to requested rate increase (decrease) requested by third parties related to incentive compensation					(3.0)		(0.6)
Public Utilities, Adjustment recommended by third parties related to return on equity					(1.6)		(0.2)
Public Utilities, Adjustment to requested rate increase (decrease) recommended by third parties related to conservation programs					0.7		(0.7)
Public Utilities, Adjustment to requested rate increase (decrease) recommended by third parties related to depreciation expense					(0.7)		(1.3)
Public Utilities, Adjustment to requested rate increase (decrease) recommended by third parties related to amortization expenses					0		(2.3)
Public Utilities, Adjustment to requested rate increase (decrease) requested by third parties related to other costs					(1.7)		(0.7)
Public Utilities, Rate increase (decrease) recommended by third parties					$ 23.8		$ (1.1)
Public Utilities, Rate increase (decrease) recommended by third parties, percentage					3.80%		(0.90%)