Asset Impairment Expense (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 0	$ 168
Alto Maipo [Member]
Asset Impairment Expense [Line Items]
Assets Carrying Amount Disclosure Nonrecurring	$ 1,500
Kazakhstan [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets to be Disposed of		94
DPL Subsidiary [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		66
Other Impairment [Member]
Asset Impairment Expense [Line Items]
Impairment of Long-Lived Assets Held-for-use		8
Long Lived Assets Held For Sale [Member] | Kazakhstan [Member]
Asset Impairment Expense [Line Items]
Assets Carrying Amount Disclosure Nonrecurring		171
Disposal Group, Including Discontinued Operation, Foreign Currency Translation Gains (Losses)			$ 92
Fair Value Less Costs To Sell		29
Impairment of Long-Lived Assets to be Disposed of			$ 94
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