Asset Impairment Expense (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017	Jun. 30, 2016
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		$ 2	$ 79		$ 260	$ 473
Parent Company [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use			23	$ 49
Kazakhstan Hydro [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets to be Disposed of		2	0		92	0
Kazakhstan [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets to be Disposed of		0	0		94	0
Buffalo Gap [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	78		0	78
buffalo gap II [Member] [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	0		0	159
DPL Subsidiary [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	0		66	235
Energy Storage [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	0		8	0
Other Impairment [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		0	$ 1		0	$ 1
Long Lived Assets Held And Used [Member] | Stuart Station [Member]
Asset Impairment Expense [Line Items]
Assets, fair value							$ 3
Long Lived Assets Held And Used [Member] | Killen Station [Member]
Asset Impairment Expense [Line Items]
Assets, fair value							$ 8	$ 84
Long Lived Assets Held And Used [Member] | DPL Peaking Generation [Domain]
Asset Impairment Expense [Line Items]
Assets, fair value								$ 5
Long Lived Assets Held And Used [Member] | buffalo gap II [Member] [Member]
Asset Impairment Expense [Line Items]
Assets, fair value				$ 92
Fair Value, Inputs, Level 3 [Member] | Long Lived Assets Held And Used [Member] | Buffalo Gap [Member]
Asset Impairment Expense [Line Items]
Assets, fair value	[1]	$ 35			$ 35

[1] (2) See Note 14—Asset Impairment Expense for further information.