Securities (Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities) (Detail) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Debt securities:
Less than 1 year	[1]	$ 1,237
1-5 years	[1]	11,927
5-10 years	[1]	14,395
Over 10 years	[1]	1,844
Equity securities		698
Available-for-sale and other securities, Amortized Cost		30,101	$ 28,678
Debt securities:
Less than 1 year	[1]	1,259
1-5 years	[1]	12,393
5-10 years	[1]	15,232
Over 10 years	[1]	1,871
Equity securities		700
Available-for-sale and other securities, fair value	[2]	31,455	29,044
Debt securities:
Less than 1 year	[1]	35
1-5 years	[1]	12
5-10 years	[1]	13
Over 10 years	[1]	2
Held-to-maturity securities, amortized cost	[3]	62	70
Debt securities:
Under 1 year	[1]	35
1-5 years	[1]	12
5-10 years	[1]	13
Over 10 years	[1]	2
Held-to-maturity securities, fair value		$ 62	$ 70

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

[2] Amortized cost of $ 30,101 and $ 28,678 at June 30, 2016 and Dec ember 31, 2015 , respectively.

[3] Fair value of $ 62 and $ 70 at June 30, 2016 and December 31, 2015 , respectively.