INCOME TAXES INCOME TAXES PROVISION (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current provision
Federal	$ (12.8)us-gaap_CurrentFederalTaxExpenseBenefit	$ (1.3)us-gaap_CurrentFederalTaxExpenseBenefit	$ 24.8us-gaap_CurrentFederalTaxExpenseBenefit
State	6.7	3.4	4.2
Total current provision	(6.1)us-gaap_CurrentIncomeTaxExpenseBenefit	2.1us-gaap_CurrentIncomeTaxExpenseBenefit	29.0us-gaap_CurrentIncomeTaxExpenseBenefit
Deferred provision
Federal	84.3	71.5	27.8
State	6.6	8.3	5.9
Total deferred provision	90.9us-gaap_DeferredIncomeTaxExpenseBenefit	79.8us-gaap_DeferredIncomeTaxExpenseBenefit	33.7us-gaap_DeferredIncomeTaxExpenseBenefit
Interest	0.2	0.3	0.1
Provision for income taxes	84.7us-gaap_IncomeTaxExpenseBenefit	81.9us-gaap_IncomeTaxExpenseBenefit	62.6us-gaap_IncomeTaxExpenseBenefit
Deferral
Deferred provision
Investment tax credits	0	0	0.2
Amortization
Deferred provision
Investment tax credits	$ (0.3)	$ (0.3)	$ (0.4)

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

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