v2.4.0.6
Parent-Only Financial Statements, Statement of Income (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Interest expense:      
Short-term borrowings $ 79 $ 80 $ 92
Long-term debt 3,110 3,978 4,888
Other interest expense 245 316 227
Noninterest expense 50,398 49,393 50,456
Income before income tax benefit and equity in undistributed income of subsidiaries 28,471 23,656 19,001
Income tax benefit 9,103 7,445 6,338
Net income 18,897 15,869 12,362
Parent Company [Member]
      
Income [Abstract]      
Interest income from subsidiaries 897 914 1,375
Other interest income 222 242 304
Other income 267 460 363
Total income 14,303 13,302 14,959
Interest expense:      
Indebtedness to nonbank subsidiaries 287 254 312
Short-term borrowings 1 1 1
Long-term debt 1,877 2,423 2,874
Other interest expense 23 8 2
Noninterest expense 1,127 77 1,335
Total expense 3,315 2,763 4,524
Income before income tax benefit and equity in undistributed income of subsidiaries 10,988 10,539 10,435
Income tax benefit (903) (584) (749)
Equity in undistributed income of subsidiaries 7,006 4,746 1,178
Net income 18,897 15,869 12,362
Parent Company [Member] | Bank [Member]
      
Income [Abstract]      
Dividends from subsidiaries 11,767 11,546 12,896
Parent Company [Member] | Nonbank [Member]
      
Income [Abstract]      
Dividends from subsidiaries $ 1,150 $ 140 $ 21