Loans and asset quality- Allowance for Credit Losses Activity (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	$ 54,036	$ 51,657
Domestic
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	39,246	38,230
Overdrafts
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	5,583	3,715
Overdrafts | Domestic
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	1,078	1,314	2,772
Margin loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	16,430	15,652
Margin loans | Domestic
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	16,430	15,652	13,242
Other | Domestic
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	$ 788	$ 768	$ 644