Information about Past Due Loans (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	$ 106	$ 268
60-89 Days past due	28	29
>90 Days past due	11	13
Total past due	145	310
Domestic
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	106	268
60-89 Days past due	28	29
>90 Days past due	11	13
Total past due	145	310
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	21	3
Total past due	70	92
Domestic | Other Residential Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	31	36
60-89 Days past due	6	10
>90 Days past due	11	13
Total past due	48	59
Domestic | Financial Institutions
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	19	36
Total past due	19	36
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 | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	7	47
60-89 Days past due	1	9
Total past due	$ 8	$ 56