Pension and Postretirement Benefits (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2011	Nov. 27, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for our defined benefit pension plans			$ 359.8	$ 382.5
Change in Discount Rate			25.00%
Funded status of defined benefit pension plan			113.96%
Defined Benefit Plan, Fair Value of Plan Assets, Other Investments			46.1
Defined Benefit Plan, Fair Value of Plan Assets			349.1
DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for our defined benefit pension plans	382.5			359.8	382.5
Funded status of defined benefit pension plan			113.96%
Defined Benefit Plan, Fair Value of Plan Assets, Other Investments			46.1	37.0
Defined Benefit Plan, Fair Value of Plan Assets			349.1	361.4
Cash Balance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage			100.00%
Defined benefit plan employee vested minimum period, years			three
Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage			100.00%
Defined benefit plan employee vested minimum period, years			five
Defined Benefit Plan [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage			100.00%
Defined benefit plan employee vested minimum period, years			five
Management Employees [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan employee vested percentage			100.00%
Defined benefit plan employee vested minimum period, years			three
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to the defined benefit plan					40.0
Expected rate of return on plan assets	8.00%	7.00%	6.75%	7.00%
Change in Expected rate of return on plan assets			1.00%
Discount rate	5.31%	4.88%	4.04%	4.88%
Discount rate for obligations	4.88%		4.86%	4.04%	4.88%
Estimated contribution to the defined benefit plans next year			0.4
Defined Benefit Plan, Fair Value of Plan Assets, Other Investments				37.0
Defined Benefit Plan, Fair Value of Plan Assets	335.9		349.1	361.4	335.9
Pension [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to the defined benefit plan					40.0
Expected rate of return on plan assets			6.75%	7.00%	8.00%
Change in Expected rate of return on plan assets			1.00%
Discount rate			4.04%	4.88%	5.31%
Change in Discount Rate			25.00%
Discount rate for obligations	4.88%		4.86%	4.04%	4.88%
Estimated contribution to the defined benefit plans next year			0.4
Equity and debt Mutual funds				310.5
Defined Benefit Plan, Fair Value of Plan Assets, Other Investments				37.0
Defined Benefit Plan, Fair Value of Plan Assets	335.9		349.1	361.4	335.9
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets	6.00%	6.00%	6.00%	6.00%
Discount rate	4.96%	4.62%	4.58%	4.62%
Discount rate for obligations	4.62%		4.58%	3.75%	4.62%
Estimated contribution to the defined benefit plans next year			1.9
Defined Benefit Plan, Fair Value of Plan Assets	4.5		3.7	4.2	4.5
Postretirement [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets			6.00%	6.00%	6.00%
Discount rate			4.58%	4.62%	4.96%
Discount rate for obligations	4.62%		4.58%	3.75%	4.62%
Estimated contribution to the defined benefit plans next year			1.9
Defined Benefit Plan, Fair Value of Plan Assets	4.5		3.7	4.2	4.5
Change in Expected Rate of Return [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase decrease In Pension Expense			3.4
Change in Expected Rate of Return [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase decrease In Pension Expense			3.4
Change in Discount Rate [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase decrease In Pension Expense			0.3
Change in Discount Rate [Member] | DP&L [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase decrease In Pension Expense			$ 0.3