Loans and asset quality- Information about Past Due Loans (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013		Jan. 18, 2008	Aug. 31, 2007
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	$ 50		$ 136
60 to 89 days past due	5		11
Greater than 90 days past due	340		7
Total past due	395		154
Legal Claim					312	312
Accrued interest on the reestablished loan	28
Domestic
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	50		136
60 to 89 days past due	5		11
Greater than 90 days past due	340		7
Total past due	395		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 | Other residential mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	20		32
60 to 89 days past due	3		6
Greater than 90 days past due	3		6
Total past due	26		44
Domestic | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	6		22
60 to 89 days past due	0		2
Greater than 90 days past due	0		0
Total past due	6		24
Domestic | Wealth management loans and mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days past due	24		45
60 to 89 days past due	2		3
Greater than 90 days past due	25		1
Total past due	51		49
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 Sept. 30, 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.