Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Investment Holdings
Amortized Cost	$ 14,652		$ 14,571
Total Unrealized Losses	(12)		(21)
Fair Value	15,263	[1]	15,207	[1]
Amortized Cost	283	[2]	284	[2]
Fair Value	283		284
Available-for-sale Securities
Investment Holdings
Amortized Cost	14,652		14,571
Unrealized Gains	623		657
Total Unrealized Losses	(12)		(21)
Fair Value	15,263		15,207
Held-to-maturity Securities
Investment Holdings
Amortized Cost	283		284
Fair Value	283		284
US Treasury and Government | Available-for-sale Securities
Investment Holdings
Amortized Cost	41		41
Fair Value	41		41
US Government-sponsored Enterprises Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	1,729		1,730
Unrealized Gains	170		181
Fair Value	1,899		1,911
US States and Political Subdivisions Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	202		203
Unrealized Gains	10		9
Fair Value	212		212
US States and Political Subdivisions Debt Securities | Held-to-maturity Securities
Investment Holdings
Amortized Cost	282		282
Fair Value	282		282
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises | Available-for-sale Securities
Investment Holdings
Amortized Cost	8,534	[3]	8,403	[3]
Unrealized Gains	314	[3]	345	[3]
Total Unrealized Losses	(4)	[3]	(18)	[3]
Fair Value	8,844	[3]	8,730	[3]
Other Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	3,087		3,161
Unrealized Gains	122		119
Total Unrealized Losses	(8)		(3)
Fair Value	3,201		3,277
Other Debt Securities | Held-to-maturity Securities
Investment Holdings
Amortized Cost	1		2
Fair Value	1		2
Equity Securities, Other | Available-for-sale Securities
Investment Holdings
Amortized Cost	1,059	[4]	1,033	[4]
Unrealized Gains	7	[4]	3	[4]
Fair Value	$ 1,066	[4]	$ 1,036	[4]

[1] Amortized cost of $14,652 and $14,571 at March 31, 2013 and December 31, 2012, respectively.

[2] Fair value of $283 and $284 at March 31, 2013 and December 31, 2012, respectively.

[3] Includes interest-only mortgage backed securities of $456 and $408 as of March 31, 2013 and December 31, 2012, 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] Other securities consist of FHLB and FRB restricted stock holdings of $497 and $347, respectively, at March 31, 2013 and December 31, 2012, that are carried at cost, and certain mutual fund and equity security holdings.