Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Loans Receivable, Net [Abstract]
Other loans included in impaired loans apart from TDR loans	$ 46	$ 92
Residential mortgage loan carried at lower of amortized cost or fair value less cost to sell	718	706
Non Accrual loans included in TDR loan	$ 362	$ 458