Discontinued Operations and Held-For-Sale Businesses (Narrative) (Details)							1 Months Ended		3 Months Ended	7 Months Ended	12 Months Ended
	Jan. 27, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jul. 01, 2015 USD ($)	Feb. 24, 2014 USD ($)	Jan. 30, 2014 USD ($)	Apr. 29, 2013 USD ($) business	Jun. 30, 2014 USD ($)	Nov. 30, 2013 USD ($) project	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Aug. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset Impairment Charges											$ 602,000,000	$ 383,000,000	$ 661,000,000
Net loss from disposal and impairments of discontinued operations											0	(56,000,000)	(152,000,000)
Income (Loss) from Continuing Operations Attributable to Parent											306,000,000	789,000,000	284,000,000
Cameroon businesses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset Impairment Charges										$ 101,000,000
Equity method investments (4)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business				$ 8,000,000
U.S. wind projects
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of ownership in subsidiary percent								100.00%
Proceeds from divestiture of business					$ 27,000,000
Asset Impairment Charges								$ 47,000,000
Fair value less costs to sell								$ 30,000,000
Number of wind projects | project								3
Asset impairment charges attributable to noncontrolling interest								$ 7,000,000
Assets carrying amount								77,000,000
Deferred proceeds from divestiture of business					$ 3,000,000
Poland wind projects
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business								7,000,000
Asset Impairment Charges								65,000,000
Net loss from disposal and impairments of discontinued operations								$ (2,000,000)
Number of wind projects | project								10
Kiev and Rivne
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business						$ 113,000,000
Asset Impairment Charges						$ 38,000,000
Number of power distribution businesses sold | business						2
Kiev
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of ownership in subsidiary percent						89.10%
Rivne
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of ownership in subsidiary percent						84.60%
Minimum | Poland wind projects
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of ownership in subsidiary percent								61.00%
Maximum | Poland wind projects
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of ownership in subsidiary percent								89.00%
Armenia Mountain
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale agreement, buyer option to purchase ownership percent								100.00%
Sale Agreement, Buyer Option To Purchase Ownership Interest, Sales Price								$ 75,000,000
Cameroon businesses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Consideration							$ 200,000,000		$ 200,000,000
Proceeds from divestiture of business							156,000,000
Net loss from disposal and impairments of discontinued operations									(7,000,000)
Cameroon businesses | Noncurrent Asset
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Non-contingent Consideration, Fair Value, Amount to be Received							$ 44,000,000		$ 44,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | DPLER
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business		$ 76,000,000
Income (Loss) from Continuing Operations Attributable to Parent											11,000,000	(129,000,000)	6,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Kelanitissa [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of ownership in subsidiary percent														90.00%
Income (Loss) from Continuing Operations Attributable to Parent											(7,000,000)	1,000,000	16,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Armenia Mountain
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent											$ 6,000,000	$ 7,000,000	$ 4,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Armenia Mountain
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business			$ 64,000,000
Subsequent Event [Member] | 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]
Proceeds from divestiture of business	$ 18,000,000