Loans and asset quality- Troubled Debt Restructurings (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2013 Contract	Jun. 30, 2013 Contract	Sep. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of contracts (contracts)	34	28	52
Outstanding recorded investment Pre-modification	$ 8	$ 5	$ 16
Outstanding recorded investment Post- modification	9	7	16
Domestic | Other residential mortgages
Financing Receivable, Modifications [Line Items]
Number of contracts (contracts)	34	28	48
Outstanding recorded investment Pre-modification	8	5	14
Outstanding recorded investment Post- modification	9	7	14
Domestic | Wealth management loans and mortgages
Financing Receivable, Modifications [Line Items]
Number of contracts (contracts)	0	0	4
Outstanding recorded investment Pre-modification	0	0	2
Outstanding recorded investment Post- modification	$ 0	$ 0	$ 2