Fair Value (Nonrecurring Measurements) (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges				$ 172	$ 260
Other Asset Impairment Charges		$ 74	$ 2	166	260
IPL Subsidiary [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Retirement Obligation		53		53
Long Lived Assets Held And Used [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges	[1]				66
Long Lived Assets Held And Used [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges	[1]			156
Long Lived Assets Held And Used [Member] | Other Subsidiaries [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges	[1]				8
Long Lived Assets Held And Used [Member] | Kazakhstan Hydro [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges	[1]				92
Long Lived Assets Held And Used [Member] | Kazakhstan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges	[1]				94
Equity Method Investments [Member] | Elsta [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges	[1]			5
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring		55		55		$ 127
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		11		11
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]	0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]	0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]	33		33
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Other Subsidiaries [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Other Subsidiaries [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Other Subsidiaries [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		7		7
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Kazakhstan Hydro [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Kazakhstan Hydro [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		92		92
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Kazakhstan Hydro [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Kazakhstan [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Kazakhstan [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		29		29
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | Kazakhstan [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]		0		0
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1],[2]		77		77
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1],[2]	185		185
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | Other Subsidiaries [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1],[2]		15		15
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | Kazakhstan Hydro [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1],[2]		190		190
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | Kazakhstan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1],[2]		$ 171		$ 171
Fair Value, Measurements, Nonrecurring [Member] | Equity Method Investments [Member] | Fair Value [Member] | Elsta [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]	0		0
Fair Value, Measurements, Nonrecurring [Member] | Equity Method Investments [Member] | Fair Value [Member] | Elsta [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]	16		16
Fair Value, Measurements, Nonrecurring [Member] | Equity Method Investments [Member] | Fair Value [Member] | Elsta [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1]	0		0
Fair Value, Measurements, Nonrecurring [Member] | Equity Method Investments [Member] | Carrying Amount [Member] | Elsta [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Nonrecurring	[1],[2]	$ 21		$ 21
Measurement Input, Long-term Revenue Growth Rate [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Weighted Average [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				(1.50%)
Measurement Input, Long-term Revenue Growth Rate [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Maximum [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				(3.00%)
Measurement Input, Long-term Revenue Growth Rate [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Minimum [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				(1.00%)
Measurement Input, Operating Margin [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Weighted Average [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				30.00%
Measurement Input, Operating Margin [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Maximum [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				36.00%
Measurement Input, Operating Margin [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Minimum [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				25.00%
Measurement Input, Discount Rate [Member] | Long Lived Assets Held And Used [Member] | Valuation, Income Approach [Member] | Weighted Average [Member] | DPL Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				9.00%
Interest Rate Contract [Member] | Measurement Input, Entity Credit Risk [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				3.63%
Interest Rate Contract [Member] | Measurement Input, Entity Credit Risk [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				4.38%
Interest Rate Contract [Member] | Measurement Input, Entity Credit Risk [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Inputs, Nonrecurring				1.78%
Argentina, Pesos | Foreign Exchange Contract [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U S Dollar Indexation In Argentina		99.2		99.2
Argentina, Pesos | Foreign Exchange Contract [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U S Dollar Indexation In Argentina		166.5		166.5
Argentina, Pesos | Foreign Exchange Contract [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U S Dollar Indexation In Argentina		42.1		42.1

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

[2] _ ⁽¹⁾  Represents the carrying values at the dates of initial measurement, before fair value adjustmen