Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Investment Holdings
Amortized Cost	$ 20,393		$ 18,409
Total Unrealized Losses	(72)		(159)
Available for sale securities	20,749	[1]	18,597	[1]
Amortized Cost	195	[2]	208	[2]
Held-to-maturity securities	195		208
Available-for-sale Securities
Investment Holdings
Amortized Cost	20,393	[3]	18,409
Unrealized Gains	428		347
Total Unrealized Losses	(72)		(159)
Available for sale securities	20,749	[3]	18,597
Held-to-maturity Securities
Investment Holdings
Amortized Cost	195	[3]	208
Held-to-maturity securities	195	[3]	208
US Treasury and Government | Available-for-sale Securities
Investment Holdings
Amortized Cost	26		26
Available for sale securities	26		26
US Government-sponsored Enterprises Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	1,522		1,523
Unrealized Gains	113		121
Available for sale securities	1,635		1,644
US States and Political Subdivisions Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	186		187
Unrealized Gains	8		5
Available for sale securities	194		192
US States and Political Subdivisions Debt Securities | Held-to-maturity Securities
Investment Holdings
Amortized Cost	194		207
Held-to-maturity securities	194		207
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Investment Holdings
Total Unrealized Losses	(64)		(150)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises | Available-for-sale Securities
Investment Holdings
Amortized Cost	14,029	[4]	12,294	[4]
Unrealized Gains	220	[4]	140	[4]
Total Unrealized Losses	(64)	[4]	(150)	[4]
Available for sale securities	14,185	[4]	12,284	[4]
Other Debt Securities
Investment Holdings
Total Unrealized Losses	(7)		(8)
Other Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	3,917		3,514
Unrealized Gains	81		76
Total Unrealized Losses	(7)		(8)
Available for sale securities	3,991		3,582
Other Debt Securities | Held-to-maturity Securities
Investment Holdings
Amortized Cost	1		1
Held-to-maturity securities	1		1
Other Debt And Equity Securities [Member]
Investment Holdings
Total Unrealized Losses	(1)		(1)
Other Debt And Equity Securities [Member] | Available-for-sale Securities
Investment Holdings
Amortized Cost	713	[5]	865	[5]
Unrealized Gains	6	[5]	5	[5]
Total Unrealized Losses	(1)	[5]	(1)	[5]
Available for sale securities	$ 718	[5]	$ 869	[5]

[1] Amortized cost of $20,393 and $18,409 at March 31, 2014 and December 31, 2013, respectively.

[2] Fair value of $195 and $208 at March 31, 2014 and December 31, 2013, respectively.

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

[4] Includes interest-only mortgage backed securities of $217 and $262 as of March 31, 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.

[5] Other securities consist of FHLB and FRB restricted stock holdings of $249 and $350, respectively, at March 31, 2014 and $402 and $349, respectively, at December 31, 2013, that are carried at cost, and certain mutual fund and equity security holdings.