Cash Flow Information (Details) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Significant Noncash Transactions
Interest paid, net of amount capitalized		$ 1,172,000,000	$ 1,067,000,000	$ 836,000,000
Income taxes paid	[1]	16,000,000	(6,000,000)	(60,000,000)
Consent Fees Paid, Preferred Stock		0	5,000,000	0
(Decrease)/additions to fixed assets for accrued capital expenditures		(24,000,000)	87,000,000	405,000,000
Decrease to fixed assets for accrued grants and related tax impact		0	711,000,000	681,000,000
Income Taxes Paid		17,000,000	15,000,000	28,000,000
Income tax refunds received		1,000,000	21,000,000	87,000,000
EME [Member]
Other Significant Noncash Transactions
Issuance of shares for GenOn acquisition		$ 0	$ (401,000,000)	$ 0

[1] In 2015, the net income taxes paid reflect $17 million in income taxes paid and $1 million in income tax refunds. In 2014, the net income taxes refunded are net of $15 million income taxes paid and $21 million income tax refunds. In 2013, the net income taxes refunded are net of $28 million income taxes paid and $87 million income tax refunds.