Fair Value Measurements (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2015

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Fair Value Measurements [Abstract]

Fair Value and Cost of Non-Derivative Instruments

	March 31, 2015				December 31, 2014
$ in millions	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets
Money market funds	$	0.1	$	0.1	$	0.1	$	0.1
Equity securities		2.7		3.8		2.7		3.7
Debt securities		4.6		4.6		4.7		4.7
Hedge funds		0.7		0.7		0.8		0.8
Real estate		0.3		0.4		0.4		0.4
Total Assets	$	8.4	$	9.6	$	8.7	$	9.7
Liabilities
Debt	$	2,159.7	$	2,238.5	$	2,159.7	$	2,204.8

	December 31, 2014				December 31, 2013
$ in millions	Cost		Fair Value		Cost		Fair Value
Assets
Money market funds	$	0.1	$	0.1	$	0.3	$	0.3
Equity securities		2.7		3.7		3.3		4.4
Debt securities		4.7		4.7		5.4		5.5
Hedge Funds		0.8		0.8		0.9		0.9
Real Estate		0.4		0.4		0.4		0.4
Total assets	$	8.7	$	9.7	$	10.3	$	11.5
Liabilities
Debt	$	2,159.7	$	2,204.8	$	2,294.4	$	2,334.6

Fair Value of Assets and Liabilities Measured on Recurring Basis

Assets and Liabilities at Fair Value
			Level 1		Level 2		Level 3
$ in millions	Fair Value at March 31, 2015		Based on Quoted Prices in Active Markets		Other Observable Inputs		Unobservable Inputs
Assets
Master Trust assets
Money market funds	$	0.1	$	0.1	$	-	$	-
Equity securities		3.8		-		3.8		-
Debt securities		4.6		-		4.6		-
Hedge funds		0.7		-		0.7		-
Real estate		0.4		-		0.4		-
Total Master Trust assets		9.6		0.1		9.5		-
Derivative Assets
FTRs		0.3		-		-		0.3
Forward power contracts		20.3		-		18.8		1.5
Total Derivative assets		20.6		-		18.8		1.8
Total Assets	$	30.2	$	0.1	$	28.3	$	1.8
Liabilities
Derivative Liabilities
Heating oil		0.3		0.3		-		-
Forward power contracts		20.4		-		19.0		1.4
Total Derivative liabilities		20.7		0.3		19.0		1.4
Long-term debt		2,238.5		-		2,220.3		18.2
Total Liabilities	$	2,259.2	$	0.3	$	2,239.3	$	19.6

Assets and Liabilities at Fair Value
			Level 1		Level 2		Level 3
$ in millions	Fair Value at December 31, 2014		Based on Quoted Prices in Active Markets		Other Observable Inputs		Unobservable Inputs
Assets
Master Trust assets
Money market funds	$	0.1	$	0.1	$	-	$	-
Equity securities		3.7		-		3.7		-
Debt securities		4.7		-		4.7		-
Hedge funds		0.8		-		0.8		-
Real estate		0.4		-		0.4		-
Total Master Trust assets		9.7		0.1		9.6		-
Derivative assets
Forward power contracts		14.9		-		13.7		1.2
Total Derivative assets		14.9		-		13.7		1.2
Total Assets	$	24.6	$	0.1	$	23.3	$	1.2
Liabilities
Derivative liabilities
FTRs	$	0.6	$	-	$	-	$	0.6
Heating oil futures		0.4		0.4		-		-
Natural gas futures		0.1		0.1		-		-
Forward power contracts		11.1		-		11.1		-
Total Derivative liabilities		12.2		0.5		11.1		0.6
Long-term debt		2,204.8		-		2,186.6		18.2
Total Liabilities	$	2,217.0	$	0.5	$	2,197.7	$	18.8

Assets and Liabilities at Fair Value
			Level 1		Level 2		Level 3
$ in millions	Fair Value at December 31, 2014 (a)		Based on Quoted Prices in Active Markets		Other observable inputs		Unobservable inputs
Assets
Master trust assets
Money market funds	$	0.1	$	0.1	$	-	$	-
Equity securities		3.7		3.7		-		-
Debt securities		4.7		4.7		-		-
Hedge Funds		0.8		-		0.8		-
Real Estate		0.4		0.4		-		-
Total Master trust assets		9.7		8.9		0.8		-
Derivative assets
Forward power contracts		14.9		-		13.7		1.2
Total derivative assets		14.9		-		13.7		1.2
Total assets	$	24.6	$	8.9	$	14.5	$	1.2
Liabilities
FTRs	$	0.6	$	-	$	-	$	0.6
Heating oil futures		0.4		0.4		-		-
Natural gas futures		0.1		0.1		-		-
Forward power contracts		11.1		-		11.1		-
Total derivative liabilities		12.2		0.5		11.1		0.6
Long-term debt		2,204.8		-		2,186.6		18.2
Total liabilities	$	2,217.0	$	0.5	$	2,197.7	$	18.8

Assets and Liabilities at Fair Value
			Level 1		Level 2		Level 3
$ in millions	Fair Value at December 31, 2013 (a)		Based on Quoted Prices in Active Markets		Other observable inputs		Unobservable inputs
Assets
Master trust assets
Money market funds	$	0.3	$	0.3	$	-	$	-
Equity securities		4.4		4.4		-		-
Debt securities		5.5		5.5		-		-
Hedge Funds		0.9		-		0.9		-
Real Estate		0.4		0.4		-		-
Total Master trust assets		11.5		10.6		0.9		-
Derivative assets
FTRs		0.2		-		-		0.2
Heating oil futures		0.2		0.2		-		-
Forward power contracts		13.4		-		13.4		-
Total derivative assets		13.8		0.2		13.4		0.2
Total assets	$	25.3	$	10.8	$	14.3	$	0.2
Liabilities
Forward power contracts	$	10.6	$	-	$	10.6	$	-
Total derivative liabilities		10.6		-		10.6		-
Long-term debt		2,334.6		-		2,316.1		18.5
Total liabilities	$	2,345.2	$	-	$	2,326.7	$	18.5

Fair Value Measurements, Nonrecurring [Table Text Block]

$ in millions	Three months ended March 31, 2014
		Carrying	Fair Value							Gross
		Amount (c)		Level 1		Level 2		Level 3		Loss
Assets
Long-lived assets (a)
DP&L (East Bend)	$	14.2	$	-	$	-	$	2.7	$	11.5
Goodwill (b)
DPLER Reporting unit	$	135.8	$	-	$	-	$	-	$	135.8

$ in millions	Year ended December 31, 2014
		Carrying	Fair Value							Gross
		Amount		Level 1		Level 2		Level 3		Loss
Assets
Long-lived assets held and used (a)
DP&L (East Bend)	$	14.2	$	-	$	-	$	2.7	$	11.5
Goodwill (b)
DPLER Reporting unit	$	135.8	$	-	$	-	$	-	$	135.8

$ in millions	Year ended December 31, 2013
		Carrying	Fair Value							Gross
		Amount		Level 1		Level 2		Level 3		Loss
Assets
Long-lived assets held and used (a)
DP&L (Conesville)	$	26.2	$	-	$	-	$	-	$	26.2
Goodwill (b)
DP&L Reporting unit	$	623.3	$	-	$	-	$	317.0	$	306.3