Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Receivables [Abstract]
Other loans included in impaired loans apart from TDR loans	$ 20	$ 92
Residential Mortgage Loan TDR Carried At Lower Of Amortized Cost Or Fair Value Less Cost To Sell	741	706	687
Non Accrual loans included in TDR loan	$ 478	$ 528