Information about Past Due Loans (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	$ 192	$ 339
60-89 Days past due	6	29
>90 Days past due	9	13
Total past due	207	381
Domestic
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	192	339
60-89 Days past due	6	29
>90 Days past due	9	13
Total past due	207	381
Domestic | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	114	118
60-89 Days past due		9
Total past due	114	127
Domestic | Wealth Management Loans and Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	49	89
60-89 Days past due	1	3
Total past due	50	92
Domestic | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due		60
60-89 Days past due		7
Total past due		67
Domestic | Other Residential Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	28	36
60-89 Days past due	5	10
>90 Days past due	9	13
Total past due	42	59
Domestic | Financial Institutions
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	1	36
Total past due	$ 1	$ 36