v2.4.0.6
Securities Available for Sale, Major Categories (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Cost $ 223,283 $ 215,571
Gross unrealized gains 12,970 10,211
Gross unrealized losses (1,054) (3,169)
Securities available for sale 235,199 222,613
Debt Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 220,946 212,642
Gross unrealized gains 12,473 9,660
Gross unrealized losses (1,005) (3,106)
Securities available for sale 232,414 219,196
US Treasury and Government [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 7,099 6,920
Gross unrealized gains 47 59
Gross unrealized losses 0 (11)
Securities available for sale 7,146 6,968
US States and Political Subdivisions [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 37,120 32,307
Gross unrealized gains 2,000 1,169
Gross unrealized losses (444) (883)
Securities available for sale 38,676 32,593
Mortgage Backed Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 125,471 127,105
Gross unrealized gains 8,034 6,987
Gross unrealized losses (321) (1,352)
Securities available for sale 133,184 132,740
Federal agencies [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 92,855 92,279
Gross unrealized gains 4,434 4,485
Gross unrealized losses (4) (10)
Securities available for sale 97,285 96,754
Residential [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 14,178 16,997
Gross unrealized gains 1,802 1,253
Gross unrealized losses (49) (414)
Securities available for sale 15,931 17,836
Commercial [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 18,438 17,829
Gross unrealized gains 1,798 1,249
Gross unrealized losses (268) (928)
Securities available for sale 19,968 18,150
Corporate debt securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 20,120 17,921
Gross unrealized gains 1,282 769
Gross unrealized losses (69) (286)
Securities available for sale 21,333 18,404
Collateralized debt obligations [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 12,726 8,650
Gross unrealized gains 557 298
Gross unrealized losses (95) (349)
Securities available for sale 13,188 8,599
Other Debt Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 18,410 19,739
Gross unrealized gains 553 378
Gross unrealized losses (76) (225)
Securities available for sale 18,887 19,892
Equity Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 2,337 2,929
Gross unrealized gains 497 551
Gross unrealized losses (49) (63)
Securities available for sale 2,785 3,417
Perpetual preferred securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 1,935 2,396
Gross unrealized gains 281 185
Gross unrealized losses (40) (54)
Securities available for sale 2,176 2,527
Other equity securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 402 533
Gross unrealized gains 216 366
Gross unrealized losses (9) (9)
Securities available for sale $ 609 $ 890