Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010		Sep. 30, 2010
Investment Holdings [Line Items]
Amortized Cost	$ 15,427		$ 14,919		$ 15,308
Unrealized Gains	812		542		676
Total Unrealized Losses	(12)		(47)		(9)
Fair Value	16,227	[1]	15,414	[1]	15,975	[1]
Amortized Cost	337	[2]	353	[2]	354	[2]
Fair Value	337		353		354
US Treasury and Government
Investment Holdings [Line Items]
Amortized Cost	201		225		300
Unrealized Gains	1		5		11
Fair Value	202		230		311
US Government-sponsored Enterprises Debt Securities
Investment Holdings [Line Items]
Amortized Cost	1,808		1,564		1,691
Unrealized Gains	182		81		160
Fair Value	1,990		1,645		1,851
US States and Political Subdivisions Debt Securities
Investment Holdings [Line Items]
Amortized Cost	101		170		191
Unrealized Gains	4		2		4
Fair Value	105		172		195
Amortized Cost	335		348		349
Fair Value	335		348		349
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Investment Holdings [Line Items]
Amortized Cost	10,413		10,570		10,878
Unrealized Gains	605		435		473
Total Unrealized Losses	(1)		(32)		(4)
Fair Value	11,017		10,973		11,347
Other Debt Securities
Investment Holdings [Line Items]
Amortized Cost	1,567		1,338		995
Unrealized Gains	17		19		28
Total Unrealized Losses	(11)		(15)		(5)
Fair Value	1,573		1,342		1,018
Amortized Cost	2		5		5
Fair Value	2		5		5
Equity Securities, Other
Investment Holdings [Line Items]
Amortized Cost	1,337	[3]	1,052	[3]	1,253	[3]
Unrealized Gains	3
Fair Value	$ 1,340	[3]	$ 1,052	[3]	$ 1,253	[3]

[1] Amortized cost of $15,427, $14,919 and $15,308 at September 30, 2011, December 31, 2010 and September 30, 2010, respectively.

[2] Fair value of $337, $353 and $354 at September 30, 2011, December 31, 2010 and September 30, 2010, respectively.

[3] Other securities consist of FHLB and FRB restricted stock holdings of $497 and $345, respectively, at September 30, 2011, $524 and $344, respectively, at December 31, 2010, and $551 and $343, respectively, at September 30, 2010, that are carried at cost, and certain mutual fund and equity security holdings.