Asset Quality - Allowance for Loan and Lease Losses and Corresponding Loan Balances (Parenthetical) (Detail) (USD $) In Billions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Receivables [Abstract]
Loans carried at fair value	$ 2.0	$ 2.1	$ 2.5