Share-Based Compensation (Information About Restricted Shares Activity) (Details) (USD $) In Millions, unless otherwise specified	11 Months Ended	12 Months Ended
	Nov. 27, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of share based compensation award granted during the period	$ 0.5	$ 0.5
Intrinsic value of share based compensation award exercised during the period	1.0	0.5
Fair value of shares that vested during the period	1.0	0.6
Unrecognized compensation expense		0.1
Weighted average period to recognize compensation expense (in years)	0 years	3 months 18 days
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of share based compensation award granted during the period	1.8	1.1
Intrinsic value of share based compensation award exercised during the period	8.6	0.4
Excess tax benefit from proceeds of share-based compensation award exercised	0.5	0.1
Fair value of shares that vested during the period	7.5	0.6
Unrecognized compensation expense		3.4
Weighted average period to recognize compensation expense (in years)	0 years	2 years 8 months 12 days
DP&L [Member] | Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of share based compensation award granted during the period	1.8	1.1
Intrinsic value of share based compensation award exercised during the period	8.6	0.4
Excess tax benefit from proceeds of share-based compensation award exercised	0.5	0.1
Fair value of shares that vested during the period	7.5	0.6
Unrecognized compensation expense		$ 3.4
Weighted average period to recognize compensation expense (in years)	0 years	2 years 8 months 12 days