Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Investment Holdings [Line Items]
Amortized Cost	$ 14,571		$ 14,614
Unrealized Gains	657		758
Total Unrealized Losses	(21)		(10)
Fair Value	15,207	[1]	15,362	[1]
Amortized Cost	284	[2]	322	[2]
Fair Value	284		322
US Treasury and Government
Investment Holdings [Line Items]
Amortized Cost	41		171
Fair Value	41		171
US Government-sponsored Enterprises Debt Securities
Investment Holdings [Line Items]
Amortized Cost	1,730		1,782
Unrealized Gains	181		180
Fair Value	1,911		1,962
US States and Political Subdivisions Debt Securities
Investment Holdings [Line Items]
Amortized Cost	203		96
Unrealized Gains	9		5
Fair Value	212		101
Amortized Cost	282		320
Fair Value	282		320
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Investment Holdings [Line Items]
Amortized Cost	8,403		9,743
Unrealized Gains	345		542
Total Unrealized Losses	(18)		(1)
Fair Value	8,730	[3]	10,284	[3]
Other Debt Securities
Investment Holdings [Line Items]
Amortized Cost	3,161		1,792
Unrealized Gains	119		29
Total Unrealized Losses	(3)		(9)
Fair Value	3,277		1,812
Amortized Cost	2		2
Fair Value	2		2
Equity Securities, Other
Investment Holdings [Line Items]
Amortized Cost	1,033	[4]	1,030	[4]
Unrealized Gains	3	[4]	2	[4]
Fair Value	$ 1,036	[4]	$ 1,032	[4]

[1] Amortized cost of $14,571 and $14,614 at December 31, 2012 and 2011, respectively.

[2] Fair value of $284 and $322 at December 31, 2012 and 2011, respectively.

[3] (a)        Includes interest-only mortgage backed securities of $408 and $110 as of December 31, 2012 and 2011, 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 Consolidated Statements of Income.

[4] (b)        Other securities consist of FHLB and FRB restricted stock holdings of $497 and $347, respectively, at December 31, 2012 and, $497 and $345, respectively, at December 31, 2011, that are carried at cost, and certain mutual fund and equity security holdings.