Fair Value Measurements (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2011
Fair Value Measurements (Textuals) [Abstract]
Level 3 assets as a percentage of total asset measured at fair value		3.00%
Percentage of mortgage backed securities included in level 3 assets measured at fair value		33.00%
Total realized/unrealized losses included in net income on liabilities still outstanding	$ 10	$ 71

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