Commitments and Contingencies (Details-4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Columbia Units [Member]
Columbia
Envrionmental civil penalty expense	$ 0.2
Accrual for future environmental mitigation projects	$ 0.6
Wisconsin Energy Efficiency and Renewables Act [Member]
Energy Efficiency and Renewables
Minimum electricity generated from renewable resources by 2015	10.00%
Environmental Protection Agency [Member]
EPA's Greenhouse Gas Reduction Guidelines
National average reduction of greenhouse gas emissions by the year 2030, percentage	30.00%
Wisconsin state average reduction goal of greenhouse gas emissions by the year 2030, percentage	34.00%
Compliance plan preparation term related to the greenhouse gas emissions reduction guidelines once the final rule is approved in 2015	2 years
EPA's National Ambient Air Quality Standards
Number of pollutants monitored by the National Ambient Air Quality Standards	6
Proposed lowered regulated level of Ozone NAAQS, minimum (in parts per billion)	65
Proposed lowered regulated level of Ozone NAAQS, maximum (in parts per billion)	70
Current regulated level of Ozone NAAQS (in parts per billion)	75
Proposed lowered regulated level of Ozone NAAQS, potential additional minimum (in parts per billion)	60
EPA's Cross State Air Pollution Rule
Number of eastern states identified contributing to pollution in other states	27
Number of phases for allocation of NOx and SO2 allowances to qualifying power plants under the rule	2
EPA's Coal Combustion Residuals Rule
Timeframe allowed to meet various compliance parameters, minimum	18 months
Timeframe allowed to meet various compliance parameters, maximum	5 years