Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Investment Holdings
Amortized Cost	$ 15,793		$ 14,571
Total Unrealized Losses	(102)		(21)
Fair Value	16,187	[1]	15,207	[1]
Amortized Cost	274	[2]	284	[2]
Fair Value	274		284
Available-for-sale Securities
Investment Holdings
Amortized Cost	15,793		14,571
Unrealized Gains	496		657
Total Unrealized Losses	(102)		(21)
Fair Value	16,187		15,207
Held-to-maturity Securities
Investment Holdings
Amortized Cost	274		284
Fair Value	274		284
US Treasury and Government | Available-for-sale Securities
Investment Holdings
Amortized Cost	26		41
Fair Value	26		41
US Government-sponsored Enterprises Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	1,624		1,730
Unrealized Gains	134		181
Fair Value	1,758		1,911
US States and Political Subdivisions Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	201		203
Unrealized Gains	4		9
Fair Value	205		212
US States and Political Subdivisions Debt Securities | Held-to-maturity Securities
Investment Holdings
Amortized Cost	273		282
Fair Value	273		282
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises | Available-for-sale Securities
Investment Holdings
Amortized Cost	9,481	[3]	8,403	[3]
Unrealized Gains	270	[3]	345	[3]
Total Unrealized Losses	(88)	[3]	(18)	[3]
Fair Value	9,663	[3]	8,730	[3]
Other Debt Securities | Available-for-sale Securities
Investment Holdings
Amortized Cost	3,483		3,161
Unrealized Gains	78		119
Total Unrealized Losses	(13)		(3)
Fair Value	3,548		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	978	[4]	1,033	[4]
Unrealized Gains	10	[4]	3	[4]
Total Unrealized Losses	(1)	[4]
Fair Value	$ 987	[4]	$ 1,036	[4]

[1] Amortized cost of $15,793 and $14,571 at June 30, 2013 and December 31, 2012, respectively.

[2] Fair value of $274 and $284 at June 30, 2013 and December 31, 2012, respectively.

[3] Includes interest-only mortgage backed securities of $483 and $408 as of June 30, 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 $348, respectively, at June 30, 2013 and $497 and $347, respectively, at December 31, 2012, that are carried at cost, and certain mutual fund and equity security holdings.