Investment Securities (Amortized Cost and Fair Value of Available-for-Sale Debt and Held-to-Maturity Securities) (Detail) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Debt securities:
Less than 1 year	[1]	$ 3
1-5 years	[1]	10,052
5-10 years	[1]	18,394
Over 10 years	[1]	4,127
Other securities		552
Available-for-sale debt securities, Amortized Cost		33,128	$ 31,577
Debt securities:
Less than 1 year	[1]	3
1-5 years	[1]	10,015
5-10 years	[1]	18,197
Over 10 years	[1]	4,063
Other securities		552
Available-for-sale debt and other securities, fair value	[2]	32,830	31,751
Debt securities:
Less than 1 year	[1]	0
1-5 years	[1]	16
5-10 years	[1]	0
Over 10 years	[1]	2
Other securities		0
Held-to-maturity securities, amortized cost	[3]	18	24
Debt securities:
Less than 1 year	[1]	0
1-5 years	[1]	16
5-10 years	[1]	0
Over 10 years	[1]	2
Other securities		0
Held-to-maturity securities, fair value		$ 18	$ 24

[1] (a) Actual maturities may differ from contractu al maturities when a right to call or prepay obligations exists with or without call or prepayment penalties.

[2] Amortized cost of $ 33,128 and $ 31,577 at December 31, 2018 and 2017 , respectively.

[3] Fair value of $ 18 and $ 24 at December 31, 2018 and 2017 , respectively .