Sales of Receivables and Servicing Rights - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015		Dec. 31, 2015
Servicing Rights at Fair Value
Residential mortgage loan sales	[1]	$ 1,114	$ 1,001	[2]
Sevicing of residential mortgage loans for other investors		57,800			$ 59,000
Amortization		$ (27)	(34)
Residential Mortgage Loans | Troubled Debt Restructuring
Servicing Rights at Fair Value
Gain on sale of HFS loans			$ 37

[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.