Acquisitions and 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
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
Loss before income taxes		(135)	[1]	(1,768)	[2]
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
Loss before income taxes				$ (49)

[1] Includes $64 million of charges related to the defeasance of Brayton Point debt and the early redemption of Kincaid debt in 2013.

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