Carrying Amount and Fair Value of Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Estimated Fair Value
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	$ 76,243	$ 90,243
Interest-bearing deposits with banks	39,782	36,381
Federal funds sold and securities purchased under resale agreements	8,543	4,510
Securities held-to-maturity	8,869	3,540
Loans	42,689	41,166
Other financial assets	5,712	5,336
Total assets	181,838	181,176
Liabilities:
Noninterest-bearing deposits	76,933	95,335
Interest-bearing deposits	144,214	123,759
Federal funds purchased and securities sold under repurchase agreements	9,162	6,267
Payables to customers and broker-dealers	13,305	12,671
Borrowings	3,127	2,376
Long-term debt	20,357	20,459
Total liabilities	267,098	260,867
Estimated Fair Value | Level 1
Assets:
Securities held-to-maturity	922
Other financial assets	4,522
Total assets	5,444
Estimated Fair Value | Level 2
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	76,243
Interest-bearing deposits with banks	39,782
Federal funds sold and securities purchased under resale agreements	8,543
Securities held-to-maturity	7,947
Loans	42,689
Other financial assets	1,190
Total assets	176,394
Liabilities:
Noninterest-bearing deposits	76,933
Interest-bearing deposits	144,214
Federal funds purchased and securities sold under repurchase agreements	9,162
Payables to customers and broker-dealers	13,305
Borrowings	3,127
Long-term debt	20,357
Total liabilities	267,098
Carrying Amount
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	76,243	90,243
Interest-bearing deposits with banks	39,743	36,321
Federal funds sold and securities purchased under resale agreements	8,543	4,510
Securities held-to-maturity	8,794	3,521
Loans	42,549	40,970
Other financial assets	5,712	5,336
Total assets	181,584	180,901
Liabilities:
Noninterest-bearing deposits	76,933	95,335
Interest-bearing deposits	144,211	123,759
Federal funds purchased and securities sold under repurchase agreements	9,162	6,267
Payables to customers and broker-dealers	13,305	12,671
Borrowings	3,127	2,376
Long-term debt	19,536	19,933
Total liabilities	$ 266,274	$ 260,341