Acquisitions and Dispositions (Details) - USD ($) $ in Millions					3 Months Ended				12 Months Ended
	Jun. 13, 2019	May 22, 2019	Apr. 07, 2017	Jun. 25, 2014	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017	Jul. 01, 2019	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	$ 28		$ 984		$ (52)
Proceeds from Divestiture of Businesses and Interests in Affiliates									178		2,020		108
Income (Loss) from Continuing Operations Attributable to Parent									(302)		(985)		507
Dispositions and Held-for-Sales Businesses
Equity method investment														$ 98
Asset Retirement Obligation, Revision of Estimate									58		24
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] | Redondo Beach [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Assets Carrying Amount Disclosure Nonrecurring									24
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Jordan [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		10		11
Proceeds from Divestiture of Businesses and Interests in Affiliates									86
Capital Contribution to Project									5
Assets Carrying Amount Disclosure Nonrecurring									$ 153
Dispositions and Held-for-Sales Businesses
Ownership interest sold									36.00%
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									$ 46		161		275
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Kilroot and Ballylumford [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									(1)		35		38
Gain (Loss) on Disposition of Business	$ 33
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 118
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									52	[1]	77	[1],[2]	17
Asset Retirement Obligation, Cash Paid to Settle									51
Dispositions and Held-for-Sales Businesses
Pre-tax gain on disposal									20
Disposal Group, Disposed of by 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									(5)		19		19
Proceeds from Divestiture of Businesses and Interests in Affiliates		$ 29
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											126
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							70
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]
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									0		9		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		0		26
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		0		33
Proceeds from Divestiture of Businesses and Interests in Affiliates													75
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]
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] | 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									0		21		39
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
Masinloc Subsidiary [Member]
Dispositions and Held-for-Sales Businesses
Ownership interest sold				45.00%											51.00%
Divestiture of Businesses, Portion Contingent Upon Achievement of Certain Restructuring Efficiencies				$ 23									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		0		$ 92
Dispositions and Held-for-Sales Businesses
Ownership interest sold													100.00%
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									87		$ 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
Assets Carrying Amount Disclosure Nonrecurring													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
Assets Carrying Amount Disclosure Nonrecurring									$ 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] After the retirement of Stuart and Killen in 2018, the Company entered into contracts to buy back all open capacity years for the plants at prices lower than the PJM capacity revenue prices. As such, the Company continued to earn capacity margin until the plants were transferred in December 2019.

[2] 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 4—Asset Retirement Obligations for further information.