Asset Impairment Expense (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($) integer	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($) integer	Mar. 31, 2016 USD ($)
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		$ 235	$ 37	$ 394	$ 45
buffalo gap II [Member] [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	$ 0	159	$ 0
UK Wind Projects [Member]
Asset Impairment Expense [Line Items]
number of projects no longer being pursued | integer			2		2
number of impaired projects | integer			4		4
Long-Lived Assets			$ 38		$ 38
Impairment of Long-Lived Assets Held-for-use		0	37	0	37
Assets, fair value			1		1
Other Impairment [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	0	0	8
Parent Company [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use				49
DPL Subsidiary [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		235	$ 0	235	$ 0
Long Lived Assets Held And Used [Member] | Killen [Member] [Member]
Asset Impairment Expense [Line Items]
Assets, fair value		84		84
Long Lived Assets Held And Used [Member] | DPL Subsidiary [Member]
Asset Impairment Expense [Line Items]
Assets, fair value		$ 5		$ 5
Long Lived Assets Held And Used [Member] | buffalo gap II [Member] [Member]
Asset Impairment Expense [Line Items]
Assets, fair value	[1]					$ 92
Long Lived Assets Held And Used [Member] | buffalo gap II [Member] [Member]
Asset Impairment Expense [Line Items]
Assets, fair value						$ 92

[1] See Note 13—Asset Impairment Expense for further information.