Loans and asset quality- Allowance for Credit Losses Activity (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 344		$ 339		$ 387
Charge-offs	(1)		(6)		(5)
Recoveries	1		5		0
Net (charge-offs) recoveries	0		(1)		(5)
Provision	(18)		6		(24)
Ending balance	326		344		358
Allowance for:
Loan losses	198		210		237
Lending-related commitments	128		134		121
Individually evaluated for impairment:
Loan balance	33		36		113
Allowance for loan losses	8		7		20
Collectively evaluated for impairment:
Loan balance	54,003		51,621		49,111
Allowance for loan losses	190		203		217
Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	83		91		104
Charge-offs	0		(1)		(2)
Recoveries	0		0		0
Net (charge-offs) recoveries	0		(1)		(2)
Provision	(4)		(7)		(5)
Ending balance	79		83		97
Allowance for:
Loan losses	20		21		22
Lending-related commitments	59		62		75
Individually evaluated for impairment:
Loan balance	13		15		54
Allowance for loan losses	3		2		7
Collectively evaluated for impairment:
Loan balance	1,741		1,519		1,297
Allowance for loan losses	17		19		15
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	41		32		30
Charge-offs	0		0		0
Recoveries	0		0		0
Net (charge-offs) recoveries	0		0		0
Provision	1		9		1
Ending balance	42		41		31
Allowance for:
Loan losses	23		21		19
Lending-related commitments	19		20		12
Individually evaluated for impairment:
Loan balance	3		3		16
Allowance for loan losses	1		1		1
Collectively evaluated for impairment:
Loan balance	2,125		1,998		1,806
Allowance for loan losses	22		20		18
Financial institutions
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	49		41		36
Charge-offs	0		0		0
Recoveries	0		3		0
Net (charge-offs) recoveries	0		3		0
Provision	(1)		5		(3)
Ending balance	48		49		33
Allowance for:
Loan losses	9		10		11
Lending-related commitments	39		39		22
Individually evaluated for impairment:
Loan balance	0		0		3
Allowance for loan losses	0		0		0
Collectively evaluated for impairment:
Loan balance	4,492		4,511		4,917
Allowance for loan losses	9		10		11
Lease financings
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	37		39		49
Charge-offs	0		0		0
Recoveries	0		0		0
Net (charge-offs) recoveries	0		0		0
Provision	(2)		(2)		(10)
Ending balance	35		37		39
Allowance for:
Loan losses	35		37		39
Lending-related commitments	0		0		0
Individually evaluated for impairment:
Loan balance	0		0		0
Allowance for loan losses	0		0		0
Collectively evaluated for impairment:
Loan balance	1,308		1,322		1,295
Allowance for loan losses	35		37		39
Wealth management loans and mortgages
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	24		18		30
Charge-offs	0		0		0
Recoveries	0		0		0
Net (charge-offs) recoveries	0		0		0
Provision	(1)		6		(1)
Ending balance	23		24		29
Allowance for:
Loan losses	18		19		25
Lending-related commitments	5		5		4
Individually evaluated for impairment:
Loan balance	10		12		31
Allowance for loan losses	2		3		7
Collectively evaluated for impairment:
Loan balance	9,912		9,731		8,888
Allowance for loan losses	16		16		18
Other residential mortgages
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	54		70		88
Charge-offs	(1)		(2)		(3)
Recoveries	1		2		0
Net (charge-offs) recoveries	0		0		(3)
Provision	(4)		(16)		(4)
Ending balance	50		54		81
Allowance for:
Loan losses	50		54		81
Lending-related commitments	0		0		0
Individually evaluated for impairment:
Loan balance	0		0		0
Allowance for loan losses	0		0		0
Collectively evaluated for impairment:
Loan balance	1,346		1,385		1,570
Allowance for loan losses	50		54		81
All Other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	0		0		2
Charge-offs	0		0		0
Recoveries	0		0		0
Net (charge-offs) recoveries	0		0		0
Provision	0		0		0
Ending balance	0		0		2
Allowance for:
Loan losses	0		0		2
Lending-related commitments	0		0		0
Individually evaluated for impairment:
Loan balance	0		0		0
Allowance for loan losses	0		0		0
Collectively evaluated for impairment:
Loan balance	18,296	[1]	17,734	[2]	16,658	[3]
Allowance for loan losses	0		0		2
Foreign
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	56		48		48
Charge-offs	0		(3)		0
Recoveries	0		0		0
Net (charge-offs) recoveries	0		(3)		0
Provision	(7)		11		(2)
Ending balance	49		56		46
Allowance for:
Loan losses	43		48		38
Lending-related commitments	6		8		8
Individually evaluated for impairment:
Loan balance	7		6		9
Allowance for loan losses	2		1		5
Collectively evaluated for impairment:
Loan balance	14,783		13,421		12,680
Allowance for loan losses	$ 41		$ 47		$ 33

[1] Includes $1,078 million of domestic overdrafts, $16,430 million of margin loans and $788 million of other loans at March 31, 2014.

[2] Includes $1,314 million of domestic overdrafts, $15,652 million of margin loans and $768 million of other loans at Dec. 31, 2013.

[3] Includes $2,772 million of domestic overdrafts, $13,242 million of margin loans and $644 million of other loans at March 31, 2013.