Discontinued Operations And Held For Sale Businesses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 MWh	Mar. 31, 2012
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Generation Capacity (MW)	125
(Gain) loss on disposal and impairment write-down - discontinued operations	$ (38)	$ 0
Discontinued Operations Income Loss
Revenue	147	191
Income (loss) from operations of discontinued businesses	13	8
Income tax (expense) benefit	1	(2)
Income (loss) from operations of discontinued businesses	14	6
Net gain/(loss) on sale and impairments of discontinued operations, net of tax	(36)	(5)
Ukraine [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Sales Proceeds, Distribution	113
Discontinued operations asset impairment	$ 38
Kiev [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Divestiture Of Ownership In Subsidiary Percent	89.10%
Customers Served	881,000
Rivne [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Divestiture Of Ownership In Subsidiary Percent	84.60%
Customers Served	412,000