Dispositions (Schedule of Disposal Groups, Including Discontinued Operations, Income Statement) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge		$ 1,600
Brayton Point and Kincaid
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenue		304		258		380
Loss before income taxes		(135)	[1]	(1,768)	[2]	(57)
Charges related to early redemption of debt		(64)
Impairment charge	48	1,600
State Line and Salem Harbor
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenue				57		233
Loss before income taxes				(49)		(34)
Impairment charge						$ 55

[1] Includes $64 million of charges related to the defeasance of Brayton Point debt and the early redemption of Kincaid debt in 2013. See Note 17 for more information.

[2] Includes a long-lived asset impairment charge of $1.6 billion.