Activity Related to Mortgage Banking Net Revenue (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Mortgage Loans On Real Estate
Residential mortgage loan sales	[1]	$ 1,114	$ 1,001	[2]
Residential mortgage loans | Troubled Debt Restructuring
Mortgage Loans On Real Estate
Residential mortgage loan sales			$ 568

[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.