Cash Flow Information (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Significant Noncash Transactions
Interest paid, net of amount capitalized		$ 1,106,000,000	$ 1,172,000,000	$ 1,067,000,000
Income taxes paid	[1]	27,000,000	16,000,000	(6,000,000)
Consent Fees Paid, Preferred Stock		0	0	5,000,000
(Decrease)/additions to fixed assets for accrued capital expenditures		(33,000,000)	(24,000,000)	87,000,000
Decrease to fixed assets for accrued grants and related tax impact		0	0	711,000,000
Income Taxes Paid		29,000,000	17,000,000	15,000,000
Income tax refunds received		2,000,000	1,000,000	21,000,000
EME [Member]
Other Significant Noncash Transactions
Issuance of shares for EME acquisition		$ 0	$ 0	$ (401,000,000)

[1] In 2016, the net income taxes paid reflect $29 million in income taxes paid and $2 million in income tax refunds. In 2015, the net income taxes refunded are net of $17 million income taxes paid and $1 million income tax refunds. In 2014, the net income taxes refunded are net of $15 million income taxes paid and $21 million income tax refunds.