Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Investment Holdings [Line Items]
Available-for-sale securities, fair value	$ 22,912	[1]	$ 18,597	[1]
Available-for-sale securities, unrealized losses	(23)		(159)
Available-for-sale securities, unrealized gains	543		347
Available-for-sale and other securities, Amortized Cost	22,392		18,409
Held-to-maturity securities, fair value	191		208
Held-to-maturity securities, amortized cost	191	[2]	208	[2]
U.S. Treasury and federal agencies
Investment Holdings [Line Items]
Available-for-sale securities, fair value	1,739		1,670
Available-for-sale securities, unrealized gains	94		121
Available-for-sale and other securities, Amortized Cost	1,645		1,549
Obligations of states and political subdivisions
Investment Holdings [Line Items]
Available-for-sale securities, fair value	193		192
Available-for-sale securities, unrealized gains	7		5
Available-for-sale and other securities, Amortized Cost	186		187
Held-to-maturity securities, fair value	190		207
Held-to-maturity securities, amortized cost	190		207
Agency mortgage-backed securities | Residential mortgage backed securities
Investment Holdings [Line Items]
Available-for-sale securities, fair value	13,060	[3]	12,284	[3]
Available-for-sale securities, unrealized losses	(8)	[3]	(150)	[3]
Available-for-sale securities, unrealized gains	306	[3]	140	[3]
Available-for-sale and other securities, Amortized Cost	12,762	[3]	12,294	[3]
Agency mortgage-backed securities | Commercial mortgage backed securities
Investment Holdings [Line Items]
Available-for-sale securities, fair value	4,255
Available-for-sale securities, unrealized losses	(11)
Available-for-sale securities, unrealized gains	40
Available-for-sale and other securities, Amortized Cost	4,226
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investment Holdings [Line Items]
Available-for-sale securities, fair value	1,569		1,395
Available-for-sale securities, unrealized losses			(1)
Available-for-sale securities, unrealized gains	45		28
Available-for-sale and other securities, Amortized Cost	1,524		1,368
Asset-backed securities and other debt securities
Investment Holdings [Line Items]
Available-for-sale securities, fair value	1,370		2,187
Available-for-sale securities, unrealized losses	(3)		(7)
Available-for-sale securities, unrealized gains	44		48
Available-for-sale and other securities, Amortized Cost	1,329		2,146
Held-to-maturity securities, fair value	1		1
Held-to-maturity securities, amortized cost	1		1
Equity securities
Investment Holdings [Line Items]
Available-for-sale securities, fair value	726	[4]	869	[4]
Available-for-sale securities, unrealized losses	(1)	[4]	(1)	[4]
Available-for-sale securities, unrealized gains	7	[4]	5	[4]
Available-for-sale and other securities, Amortized Cost	$ 720	[4]	$ 865	[4]

[1] Amortized cost of $22,392 and $18,409 at September 30, 2014 and December 31, 2013, respectively.

[2] Fair value of $191 and $208 at September 30, 2014 and December 31, 2013, respectively.

[3] Includes interest-only mortgage-backed securities of $192 and $262 as of September 30, 2014 and December 31, 2013, respectively, recorded at fair value with fair value changes recorded in securities gains, net and securities gains, net non-qualifying hedges on mortgage servicing rights in the Condensed Consolidated Statements of Income.

[4] Equity securities consist of FHLB and FRB restricted stock holdings of $249 and $351, respectively, at September 30, 2014 and $402 and $349, respectively, at December 31, 2013, that are carried at cost, and certain mutual fund and equity security holdings.