Carrying Amount and Fair Value of Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Estimated Fair Value
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	$ 62,030	$ 90,243
Interest-bearing deposits with banks	34,902	36,381
Federal funds sold and securities purchased under resale agreements	5,437	4,510
Securities held-to-maturity	4,849	3,540
Loans	40,180	41,166
Other financial assets	5,489	5,336
Total assets	152,887	181,176
Liabilities:
Noninterest-bearing deposits	65,027	95,335
Interest-bearing deposits	127,436	123,759
Federal funds purchased and securities sold under repurchase agreements	8,285	6,267
Payables to customers and broker-dealers	12,959	12,671
Borrowings	3,365	2,376
Long-term debt	21,003	20,459
Total liabilities	238,075	260,867
Estimated Fair Value | Level 1
Assets:
Securities held-to-maturity	905
Other financial assets	4,333
Total assets	5,238
Estimated Fair Value | Level 2
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	62,030
Interest-bearing deposits with banks	34,902
Federal funds sold and securities purchased under resale agreements	5,437
Securities held-to-maturity	3,944
Loans	40,180
Other financial assets	1,156
Total assets	147,649
Liabilities:
Noninterest-bearing deposits	65,027
Interest-bearing deposits	127,436
Federal funds purchased and securities sold under repurchase agreements	8,285
Payables to customers and broker-dealers	12,959
Borrowings	3,365
Long-term debt	21,003
Total liabilities	238,075
Carrying Amount
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	62,030	90,243
Interest-bearing deposits with banks	34,854	36,321
Federal funds sold and securities purchased under resale agreements	5,437	4,510
Securities held-to-maturity	4,819	3,521
Loans	40,074	40,970
Other financial assets	5,489	5,336
Total assets	152,703	180,901
Liabilities:
Noninterest-bearing deposits	65,027	95,335
Interest-bearing deposits	127,435	123,759
Federal funds purchased and securities sold under repurchase agreements	8,285	6,267
Payables to customers and broker-dealers	12,959	12,671
Borrowings	3,365	2,376
Long-term debt	20,336	19,933
Total liabilities	$ 237,407	$ 260,341