Dispositions Dispositions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from the sale of business interests, net of cash and restricted cash sold	$ 0		$ 1,180
Gain (loss) on disposal and sale of businesses interests	4		(788)
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			16
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
Proceeds from the sale of business interests, net of cash and restricted cash sold			1,050
Gain (loss) on disposal and sale of businesses interests			777
Tax on gain (loss) on disposition of business			155
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
Proceeds from the sale of business interests, net of cash and restricted cash sold			239
Gain (loss) on disposal and sale of businesses interests			(2)
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]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			(12)
Asset Retirement Obligation, Cash Paid to Settle			(15)
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]
Assets Carrying Amount Disclosure Nonrecurring	105
Proceeds from the sale of business interests, net of cash and restricted cash sold	86
Capital Contribution to Project	5
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]
Assets Carrying Amount Disclosure Nonrecurring	30
Proceeds from the sale of business interests, net of cash and restricted cash sold		$ 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
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 disposal and sale of businesses interests			$ 23
Jordan [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group Not Discontinued Operation Ownership Interest Sold	36.00%