XML 21 R124.htm IDEA: XBRL DOCUMENT v2.4.0.6
Fair Value (Details 8) (Variable interest entities, USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Variable interest entities
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Contractual principal balance $ 2,707 $ 2,954
Excess of estimated fair value over contractual principal balance 114 114
Carrying value at estimated fair value $ 2,821 $ 3,068