Significant Accounting Policies (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 percent	Mar. 31, 2011 percent	Dec. 31, 2011
Significant Accounting Policies [Line Items]
Effective Income Tax Rate, Continuing Operations	32.00%	37.00%
Unrecognized Tax Benefits	$ 4		$ 4
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	30
Collateral Already Posted, Aggregate Fair Value	138
Cash Collateral Paid or Received for Derivative Assets	1
Cash Collateral Paid or Received for Derivative Liabilities	127
Cash Collateral Paid	15
Cash Collateral Received	$ 3
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