Significant Accounting Policies (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Significant Accounting Policies [Line Items]
Receivables Due Date	21 days
Threshold Period Past Due for Write-off of Trade Accounts Receivable	150 days
Unbilled revenues included in customer accounts receivable	$ 723	$ 697
Expense Related to Refueling Outages	26	12
Period Expenses Related To Refueling Outages Are Accrued	18 months
Excise Sales Tax Net Impact on Statement of Operations	0
Unbilled Revenues [Member]
Significant Accounting Policies [Line Items]
Unbilled revenues included in customer accounts receivable	280	275
Minimum [Member]
Significant Accounting Policies [Line Items]
Notes Receivable Considered Delinquent Period	60 days
Maximum [Member]
Significant Accounting Policies [Line Items]
Notes Receivable Considered Delinquent Period	120 days
Parent Company [Member]
Significant Accounting Policies [Line Items]
Allocated Share-based Compensation Expense	$ 58	$ 42	$ 30