Loans and asset quality- Information about Past Due Loans (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Jan. 18, 2008	Aug. 31, 2007
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	$ 114		$ 136
60 to 89 days past due	5		11
Greater than 90 days past due	320		7
Total past due	439		154
Legal Claim					312	312
Domestic
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	114		136
60 to 89 days past due	5		11
Greater than 90 days past due	320		7
Total past due	439		154
Domestic | Financial institutions
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	0	[1]	37	[1]
60 to 89 days past due	0	[1]	0	[1]
Greater than 90 days past due	312	[1]	0	[1]
Total past due	312	[1]	37	[1]
Domestic | Wealth management loans and mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	57		45
60 to 89 days past due	0		3
Greater than 90 days past due	1		1
Total past due	58		49
Domestic | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	42		22
60 to 89 days past due	0		2
Greater than 90 days past due	0		0
Total past due	42		24
Domestic | Other residential mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	15		32
60 to 89 days past due	5		6
Greater than 90 days past due	7		6
Total past due	27		44
Foreign
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	0		0
60 to 89 days past due	0		0
Greater than 90 days past due	0		0
Total past due	$ 0		$ 0

[1] Past due loans at March 31, 2014 include a loan to an asset manager, Sentinel Management Group, Inc. (“Sentinel”), which was reestablished as a fully collateralized performing loan in the first quarter of 2014.