Financial and Other Derivative Instruments (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1
Letters of Credit Outstanding, Amount	19	63
Cash Collateral Posted Net of Cash Collateral Received	12
Cash Collateral Paid or Received for Derivative Assets	26	0
Cash Collateral Paid or Received for Derivative Liabilities	17
Cash Collateral Paid	34	4
Cash Collateral Received	13	24
Value of Transactions Company Would Have Been Exposed to if Credit Rating Below Investment Grade	406
Derivative, Net Liability Position, Aggregate Fair Value	1,176
Collateral Already Posted, Aggregate Fair Value	902	20
Additional Collateral, Aggregate Fair Value	249
FTR [Member]
Derivative [Line Items]
Derivative Instruments Recoverable Through PSCR Mechanism	5	15
Credit Risk Contract [Member]
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 25