Derivatives and Hedging Activities - Pre-Tax Net Gains (Losses) on Fair Value Hedges (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative	$ 1	$ 103
Net Gains (Losses) on Hedged Item	97	21
Other Income [Member] | Interest Rate [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative	(95)	(20)
Net Gains (Losses) on Hedged Item	97	21
Interest Expense [Member] | Interest Rate [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative	$ 96	$ 123