Acquisitions and Dispositions (Dispositions Narrative) (Details) $ in Millions			1 Months Ended
	Dec. 29, 2016 USD ($) MW	Dec. 20, 2016 USD ($) MW	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses			$ 1,900
DEI Latin American [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Owned Plant Capacity | MW		2,230
Enterprise Value		$ 1,200
DEI Brazil Holdings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Owned Plant Capacity | MW	2,090
Enterprise Value	$ 1,200
Obligations [Member] | International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Tax obligations				$ 54	$ 78