v2.4.0.6
Securities Available for Sale, Major Categories (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]    
Cost $ 236,990 $ 223,283
Gross unrealized gains 12,222 12,970
Gross unrealized losses (1,052) (1,054)
Securities available for sale 248,160 235,199
Debt Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 234,727 220,946
Gross unrealized gains 11,673 12,473
Gross unrealized losses (1,019) (1,005)
Securities available for sale 245,381 232,414
US Treasury and Government [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 6,862 7,099
Gross unrealized gains 34 47
Gross unrealized losses (12) 0
Securities available for sale 6,884 7,146
US States and Political Subdivisions [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 38,925 37,120
Gross unrealized gains 1,932 2,000
Gross unrealized losses (401) (444)
Securities available for sale 40,456 38,676
Mortgage Backed Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 133,840 125,471
Gross unrealized gains 7,219 8,034
Gross unrealized losses (408) (321)
Securities available for sale 140,651 133,184
Federal agencies [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 101,876 92,855
Gross unrealized gains 3,767 4,434
Gross unrealized losses (171) (4)
Securities available for sale 105,472 97,285
Residential [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 13,472 14,178
Gross unrealized gains 1,829 1,802
Gross unrealized losses (42) (49)
Securities available for sale 15,259 15,931
Commercial [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 18,492 18,438
Gross unrealized gains 1,623 1,798
Gross unrealized losses (195) (268)
Securities available for sale 19,920 19,968
Corporate debt securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 20,223 20,120
Gross unrealized gains 1,286 1,282
Gross unrealized losses (60) (69)
Securities available for sale 21,449 21,333
Collateralized loan and other debt obligations [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 16,085 12,726
Gross unrealized gains 647 557
Gross unrealized losses (69) (95)
Securities available for sale 16,663 13,188
Other Debt Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 18,792 18,410
Gross unrealized gains 555 553
Gross unrealized losses (69) (76)
Securities available for sale 19,278 18,887
Equity Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 2,263 2,337
Gross unrealized gains 549 497
Gross unrealized losses (33) (49)
Securities available for sale 2,779 2,785
Perpetual preferred securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 1,930 1,935
Gross unrealized gains 357 281
Gross unrealized losses (25) (40)
Securities available for sale 2,262 2,176
Other equity securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Cost 333 402
Gross unrealized gains 192 216
Gross unrealized losses (8) (9)
Securities available for sale $ 517 $ 609