COMMITMENTS AND CONTINGENCIES (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	1 Months Ended
	Sep. 30, 2013 Natural Gas Utility Manufactured Gas Plant Remediation site	Mar. 31, 2013 Electric Utility Weston and Pulliam Plants	Jun. 30, 2013 Electric Utility Columbia And Edgewater	Sep. 30, 2013 Electric Utility WDNR Issued NOV's NOV	Sep. 30, 2013 Electric Utility Mercury emission MW
Air Permitting Violation Claims
Beneficial environmental project amount		$ 6.0	$ 1.3
Civil penalty and/or legal fees		1.2	0.4
Number of NOV's alleging violations of the air permits received since 2008				4
Number of corrective actions taken for NOV's received				5
Mercury and Interstate Air Quality Rules
Percentage mercury reduction required by the State of Wisconsin's mercury rule through 2014					40.00%
Level of electric generating units above which a 90% reduction in mercury emissions is required by 2015 (in MW)					150
Percentage mercury reduction by 2015 required by the State of Wisconsin's mercury rule, for electric generating units above 150 MW					90.00%
Level of electric generating units above which a reduction in mercury emissions is required by the Best Available Control Technology rule (in MW)					25
Highest level for electric generating units for which a reduction in mercury emissions is required by the Best Available Control Technology rule (in MW)					150
Estimated capital cost to achieve required emission reduction					9
Manufactured Gas Plant Remediation
Number of environmental remediation sites	10
Number of environmental remediation sites transferred to the EPA Superfund Alternative Sites Program	7
Estimated and accrued future undiscounted investigation and cleanup costs for all sites	64.9
Cash expenditures for environmental remediation not yet recovered in rates	13.0
Regulatory assets recorded for cash and estimated future remediation expenditures, net of insurance recoveries received	77.9
Insurance recoveries received	$ 25.8