Mortgage Servicing Rights - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Transfers and Servicing of Financial Assets [Abstract]
Residential mortgage loans serviced for others including subserviced mortgages with no corresponding MSRs asset	$ 224,600,000,000		$ 224,600,000,000		$ 226,800,000,000
Gain/Loss on fair value changes of MSRs due to changes in valuation assumptions and derivatives used to economically hedge MSRs	49,000,000	108,000,000	200,000,000	163,000,000
Loan servicing fees	178,000,000	192,000,000	551,000,000	566,000,000
Gain related to excess servicing rights sold	$ 44,000,000