Financial and Other Derivative Instruments (Details Textuals) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1
Letters of Credit Outstanding, Amount	18	19
Cash Collateral Posted Net of Cash Collateral Received	26	12
Cash Collateral Paid or Received for Derivative Assets	5	26
Cash Collateral Paid or Received for Derivative Liabilities	7	17
Cash Collateral Received	6	13
Cash Collateral Paid	30	34
Value of Transactions Company Would Have Been Exposed to if Credit Rating Below Investment Grade	331
Derivative, Net Liability Position, Aggregate Fair Value	1,082
Collateral Already Posted, Aggregate Fair Value	962
Additional Collateral, Aggregate Fair Value	102
Credit Risk Contract [Member]
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 18