Consolidated Statements of Results of Operations (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues	$ 494.5us-gaap_ElectricUtilityRevenue	$ 460.3us-gaap_ElectricUtilityRevenue
Cost of revenues:
Fuel	76.4us-gaap_FuelCosts	90.0us-gaap_FuelCosts
Purchased power	194.2us-gaap_CostOfPurchasedPower	174.1us-gaap_CostOfPurchasedPower
Amortization of intangibles		0.3us-gaap_CostOfGoodsSoldAmortization
Total cost of revenues	270.6us-gaap_CostOfGoodsSoldElectric	264.4us-gaap_CostOfGoodsSoldElectric
Gross margin	223.9us-gaap_GrossProfit	195.9us-gaap_GrossProfit
Operating expenses:
Operation and maintenance	91.7	104.7
Depreciation and amortization	35.0	35.3
General taxes	24.1	27.6
Goodwill Impairment		135.8us-gaap_GoodwillImpairmentLoss
Fixed asset impairment		11.5
Other	0.5	0.3
Total operating expenses	151.3us-gaap_OperatingExpenses	315.2us-gaap_OperatingExpenses
Operating income	72.6us-gaap_OperatingIncomeLoss	(119.3)us-gaap_OperatingIncomeLoss
Other income / (expense), net:
Investment income/ (loss)	(0.2)us-gaap_InvestmentIncomeNet	0.4us-gaap_InvestmentIncomeNet
Interest expense	(30.5)us-gaap_InterestAndDebtExpense	(30.8)us-gaap_InterestAndDebtExpense
Other deductions	(0.5)us-gaap_OtherNonoperatingIncomeExpense	(0.5)us-gaap_OtherNonoperatingIncomeExpense
Total other income / (expense), net	(31.2)us-gaap_NonoperatingIncomeExpense	(30.9)us-gaap_NonoperatingIncomeExpense
Earnings before income tax	41.4	(150.2)
Income tax expense	12.7us-gaap_IncomeTaxExpenseBenefit	98.8us-gaap_IncomeTaxExpenseBenefit
Net income/ (loss)	28.7us-gaap_ProfitLoss	(249.0)us-gaap_ProfitLoss
Successor [Member]
Revenues			1,763.0	1,636.9	1,668.4
Cost of revenues:
Fuel			304.5	366.7	361.9
Purchased power			592.6	389.0	342.1
Amortization of intangibles			1.2	7.1	95.1
Total cost of revenues			898.3	762.8	799.1
Gross margin			864.7	874.1	869.3
Operating expenses:
Operation and maintenance			388.3	396.7	406.4
Depreciation and amortization			139.8	132.9	125.4
General taxes			91.7	80.9	79.5
Goodwill Impairment			135.8	306.3	1,817.2
Fixed asset impairment			11.5	26.2
Other			(3.9)	2.5	0.2
Total operating expenses			763.2	945.5	2,428.7
Operating income			101.5	(71.4)	(1,559.4)
Other income / (expense), net:
Investment income/ (loss)			0.9	1.4	2.5
Interest expense			(126.6)	(124.0)	(122.9)
Charge for early redemption of debt			(30.9)	(2.8)
Other deductions			(1.5)	(2.9)	(2.3)
Total other income / (expense), net			(158.1)	(128.3)	(122.7)
Earnings before income tax			(56.6)	(199.7)	(1,682.1)
Income tax expense			18.0	22.3	47.7
Net income/ (loss)			$ (74.6)	$ (222.0)	$ (1,729.8)

The amount of expense recognized in the current period that reflects the allocation of the costs of intangible assets over the expected benefit period of such assets. This element applies only to intangible assets used in the production of goods.

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