Pension and Postretirement Benefits (Effect of Change in Health Care Cost Trend Rate) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Service cost plus interest cost, One-percent increase	$ 0.1
Service cost plus interest cost, One-percent decrease	(0.1)
Benefit obligation, One-percent increase	0.9
Benefit obligation, One-percent decrease	(0.8)
DP&L [Member]
Service cost plus interest cost, One-percent increase	0.1
Service cost plus interest cost, One-percent decrease	(0.1)
Benefit obligation, One-percent increase	0.9
Benefit obligation, One-percent decrease	$ (0.8)