Acquisitions and Dispositions (Details) - USD ($) $ in Millions						3 Months Ended							6 Months Ended	12 Months Ended
	Apr. 07, 2017	Feb. 18, 2016	Jan. 27, 2016	Jan. 01, 2016	Jun. 25, 2014	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016	Mar. 20, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business						$ 128	$ (21)	$ 89	$ 788		$ (48)			$ 984		$ (52)	$ 29
Proceeds from Divestiture of Businesses and Interests in Affiliates														2,020		108	538
Income (Loss) from Continuing Operations Attributable to Parent														(985)		507	20
Dispositions and Held-for-Sales Businesses
Proceeds from Sale of Ownership Interests														0		94	0
Asset Retirement Obligation, Revision of Estimate														24		25
Jordan [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business		$ 4
Dispositions and Held-for-Sales Businesses
Ownership interest sold		40.00%
Disposal Group, Including Discontinued Operation, Consideration		$ 21
Masinloc Subsidiary [Member]
Dispositions and Held-for-Sales Businesses
Sale of Stock, Consideration Received on Transaction					$ 436
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Shady Point [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														19
Proceeds from Divestiture of Businesses and Interests in Affiliates														30
Assets Carrying Amount Disclosure Nonrecurring						30								30
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Redondo Beach [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Assets Carrying Amount Disclosure Nonrecurring						24								24
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														107		218	166
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | DPL Subsidiary [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														77	[1],[2]	17	0
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Compania Transmisora del Norte Grande [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business														129
Proceeds from Divestiture of Businesses and Interests in Affiliates														225
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Beckjord Facility [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Asset Retirement Obligation, Cash Paid to Settle									15
Dispositions and Held-for-Sales Businesses
Pre-tax gain on disposal									(12)
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Electrica Santiago (Gener ESSA) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business														69
Proceeds from Divestiture of Businesses and Interests in Affiliates														287
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | DPL Peaking Generation [Domain]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														7		17	20
Gain (Loss) on Disposition of Business									(2)
Proceeds from Divestiture of Businesses and Interests in Affiliates														239
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Masinloc Subsidiary [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														9		103	103
Gain (Loss) on Disposition of Business														772
Proceeds from Divestiture of Businesses and Interests in Affiliates														1,050
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Zimmer and Miami Fort [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														0		26	(14)
Gain (Loss) on Disposition of Business										$ 13
Proceeds from Divestiture of Businesses and Interests in Affiliates										$ 70
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Kazakhstan Hydro [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														0		33	34
Proceeds from Divestiture of Businesses and Interests in Affiliates																75
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | UK Wind Projects
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business												$ (20)
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Kelanitissa [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business			$ (5)
Proceeds from Divestiture of Businesses and Interests in Affiliates			$ 18
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Kazakhstan [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														0		13	12
Gain (Loss) on Disposition of Business	$ (49)
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 24
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | DPLER [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business				$ 49
Proceeds from Divestiture of Businesses and Interests in Affiliates				$ 76
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Other Subsidiaries [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax														14		$ 9	11
Disposal Group, Not Discontinued Operations [Member] | Advancion Energy Storage [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business									$ 23
IPP4 [Member]
Dispositions and Held-for-Sales Businesses
Noncontrolling Interest, Ownership Percentage by Parent										36.00%						36.00%
Masinloc Subsidiary [Member]
Dispositions and Held-for-Sales Businesses
Ownership interest sold					45.00%					100.00%						100.00%		51.00%
Divestiture of Businesses, Portion Contingent Upon Achievement of Certain Restructuring Efficiencies					$ 23
Kazakhstan Hydro [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of														0		$ 92	$ 0
Kazakhstan Hydro [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Kazakhstan Hydro [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Business													$ (33)
DPL Subsidiary [Member]
Dispositions and Held-for-Sales Businesses
Asset Retirement Obligation, Revision of Estimate														(32)
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | DPL Peaking Generation [Domain]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of														109
Fair Value Less Costs To Sell						237								237
Assets Carrying Amount Disclosure Nonrecurring						$ 346								346
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Kazakhstan Hydro [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of														92
Fair Value Less Costs To Sell											92		92
Assets Carrying Amount Disclosure Nonrecurring											$ 190		$ 190
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | DPL Subsidiary [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment of Long-Lived Assets to be Disposed of														$ 66

[1] Reductions in the asset retirement obligations for ash ponds and landfills at Stuart and Killen in 2018 resulted in a $32 million reduction to cost of sales. See Note 3—Property, Plant and Equipment for further information.

[2] The Company entered into contracts to buy back all open capacity years for Stuart and Killen at prices lower than the PJM capacity revenue prices. As such, the Company continues to earn capacity margin.