Significant Accounting Policies (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years percent months Days	Dec. 31, 2010	Dec. 31, 2009
Significant Accounting Policies [Line Items]
Maturities on Temporary Investments	3
Receivables Due Date	21
Specific Review of Probable Future Collections Based on Receivable Balances in Excess of 90 Days	30
Unbilled Contracts Receivable	$ 597	$ 575
Notes Receivable Considered Delinquent Minimum Due Date	60
Notes Receivable Considered Delinquent Maximum Due Date	120
LIFO Inventory Amount	52	43
Excess of Replacement or Current Costs over Stated LIFO Value	95	147
Expense Related to Refueling Outages	23	3
Period Expenses Related To Refueling Outages Are Accrued	18
Finite-Lived Intangible Assets, Useful Life, Minimum	3
Finite-Lived Intangible Assets, Useful Life, Maximum	20
Amortization of Intangible Assets	5	4	4
Finite-Lived Intangible Assets, Future Amortization Expense	3
Collateral Already Posted, Aggregate Fair Value	71	77
Cash Collateral Paid or Received for Derivative Assets	19	9
Cash Collateral Paid or Received for Derivative Liabilities	74	53
Cash Collateral Received		2
Cash Collateral Paid	$ 16	$ 35
Contract Intangible Assets [Member]
Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Useful Life, Minimum	3
Finite-Lived Intangible Assets, Useful Life, Maximum	20