Activity Related to Mortgage Banking Net Revenue (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale
Residential mortgage loan sales	$ 1,001	[1],[2]	$ 1,672	[1]
Origination fees and gains on loan sales	44		41
Servicing fees	$ 59		$ 62

[1] Represents the unpaid principal balance at the time of the sale.

[2] Excludes $568 of HFS residential mortgage loans previously modified in a TDR that were sold during the first quarter of 2015.