v2.4.0.6
Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Securities Available for Sale and Securities Held to Maturity (Detail) (USD $)
In Millions, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Investment [Line Items]    
Securities available for sale Amortized Cost $ 41,948 $ 33,950
Securities available for sale Gross Unrealized Gains 588 288
Securities available for sale Gross Unrealized Losses 88 273
Securities available for sale 42,448 33,965
Securities held to maturity 15,612 15,108
Securities held to maturity Gross Unrealized Gains 618 433
Securities held to maturity Gross Unrealized Losses 1 2
Securities held to maturity, fair value 16,229 15,539
U.S. agency residential mortgage-backed securities
   
Investment [Line Items]    
Securities available for sale Amortized Cost 23,298 20,666
Securities available for sale Gross Unrealized Gains 480 269
Securities available for sale Gross Unrealized Losses 6 14
Securities available for sale 23,772 [1] 20,921
Securities held to maturity 15,450 14,770
Securities held to maturity Gross Unrealized Gains 618 430
Securities held to maturity Gross Unrealized Losses 1 2
Securities held to maturity, fair value 16,067 [1] 15,198
Other securities
   
Investment [Line Items]    
Securities held to maturity 162 338
Securities held to maturity Gross Unrealized Gains   3
Securities held to maturity, fair value 162 341
Non-agency residential mortgage-backed securities
   
Investment [Line Items]    
Securities available for sale Amortized Cost 856 1,130
Securities available for sale Gross Unrealized Gains 3  
Securities available for sale Gross Unrealized Losses 77 223
Securities available for sale 782 [1] 907
Corporate debt securities
   
Investment [Line Items]    
Securities available for sale Amortized Cost 5,555 3,592
Securities available for sale Gross Unrealized Gains 56 5
Securities available for sale Gross Unrealized Losses 1 26
Securities available for sale 5,610 3,571
Certificates of deposit
   
Investment [Line Items]    
Securities available for sale Amortized Cost 5,524 3,623
Securities available for sale Gross Unrealized Gains 14 2
Securities available for sale Gross Unrealized Losses 2 3
Securities available for sale 5,536 3,622
Commercial paper
   
Investment [Line Items]    
Securities available for sale Amortized Cost 449 225
Securities available for sale 449 225
U.S. agency notes
   
Investment [Line Items]    
Securities available for sale Amortized Cost 350 1,795
Securities available for sale Gross Unrealized Gains   5
Securities available for sale 350 1,800
Asset-backed and other securities
   
Investment [Line Items]    
Securities available for sale Amortized Cost 5,916 2,919
Securities available for sale Gross Unrealized Gains 35 7
Securities available for sale Gross Unrealized Losses 2 7
Securities available for sale $ 5,949 $ 2,919
[1] Residential mortgage-backed securities have been allocated over maturity groupings based on final contractual maturities. Actual maturities will differ from final contractual maturities because borrowers on a certain portion of loans underlying these securities have the right to prepay their obligations.