v2.4.0.6
Securities Available for Sale, Residential Mortgage-Backed Securities, Credit Loss Component (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Credit Impairment Losses On Residential Mortgage Backed Securities [Abstract]    
Securities available for sale $ 38 $ 51
Residential [Member]
   
Credit Impairment Losses On Residential Mortgage Backed Securities [Abstract]    
Securities available for sale 15 14
Significant inputs (non-agency - non-investment grade MBS) [Abstract]    
Expected remaining life of loan losses From 1.00% 1.00%
Expected remaining life of loan losses To 20.00% 44.00%
Credit impairment distribution [Abstract]    
0 - 10% range 94.00% 46.00%
10 - 20% range 4.00% 11.00%
20 - 30% range 2.00% 1.00%
Greater than 30% 0.00% 42.00%
Weighted average 6.00% 9.00%
Current subordination levels [Abstract]    
Current subordination levels From 0.00% 0.00%
Current subordination levels To 41.00% 57.00%
Current subordination levels Weighted average 0.00% 2.00%
Prepayment speed (annual CPR)    
Prepayment speed From 4.00% 5.00%
Prepayment speed To 18.00% 29.00%
Prepayment speed Weighted average 14.00% 15.00%
Non-investment Grade [Member] | Residential [Member]
   
Credit Impairment Losses On Residential Mortgage Backed Securities [Abstract]    
Securities available for sale $ 15 $ 14