MSR (Sales of Receivables and Servicing Rights - Additional Information) (Detail) - USD ($)		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015		Dec. 31, 2015
Mortgage Loans On Real Estate
Residential mortgage loan sales	[1]	$ 1,846,000,000	$ 1,421,000,000		$ 4,591,000,000	$ 3,798,000,000	[2]
Sevicing of residential mortgage loans for other investors		54,600,000,000			54,600,000,000			$ 59,000,000,000
Amortization		$ (35,000,000)	$ (37,000,000)		$ (96,000,000)	$ (111,000,000)
Residential Mortgage Loans | Troubled Debt Restructuring
Mortgage Loans On Real Estate
Gain on sale of HFS loans				$ 37,000,000
Residential mortgage loan sales				$ 568,000,000

[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 .