Securities with Unrealized Losses, Aggregated by Category and Period of Continuous Unrealized Loss (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Investment [Line Items]
Securities available for sale Less than 12 months Fair Value	$ 3,630		$ 11,094
Securities available for sale Less than 12 months Unrealized Losses	11		57
Securities available for sale 12 months or longer Fair Value	1,344		898
Securities available for sale 12 months or longer Unrealized Losses	153		216
Total Securities available for sale with unrealized losses Total Fair Value	4,974		11,992
Total Securities available for sale with unrealized losses Total Unrealized Losses	164		273
Securities held to maturity Less than 12 months Fair Value	215		384
Securities held to maturity Less than 12 months Unrealized Losses	2		2
Securities held to maturity 12 months or longer Fair Value
Securities held to maturity 12 months or longer Unrealized Losses
Total Securities held to maturity with unrealized losses Total Fair Value	215		384
Total Securities held to maturity with unrealized losses Total Unrealized Losses	2		2
Securities Less than 12 months Fair Value	3,845	[1]	11,478	[2]
Securities Less than 12 months Unrealized Losses	13	[1]	59	[2]
Securities 12 months or longer Fair Value	1,344	[1]	898	[2]
Securities 12 months or longer Unrealized Losses	153	[1]	216	[2]
Total securities with unrealized losses Total Fair Value	5,189	[1]	12,376	[2]
Total securities with unrealized losses Total Unrealized Losses	166	[1]	275	[2]
U.S. agency residential mortgage-backed securities
Investment [Line Items]
Securities available for sale Less than 12 months Fair Value	860		5,551
Securities available for sale Less than 12 months Unrealized Losses	4		14
Securities available for sale 12 months or longer Fair Value	243
Securities available for sale 12 months or longer Unrealized Losses	4
Total Securities available for sale with unrealized losses Total Fair Value	1,103		5,551
Total Securities available for sale with unrealized losses Total Unrealized Losses	8		14
Securities held to maturity Less than 12 months Fair Value	116		384
Securities held to maturity Less than 12 months Unrealized Losses	1		2
Securities held to maturity 12 months or longer Fair Value
Securities held to maturity 12 months or longer Unrealized Losses
Total Securities held to maturity with unrealized losses Total Fair Value	116		384
Total Securities held to maturity with unrealized losses Total Unrealized Losses	1		2
Non-agency residential mortgage-backed securities
Investment [Line Items]
Securities available for sale Less than 12 months Fair Value			121
Securities available for sale Less than 12 months Unrealized Losses			8
Securities available for sale 12 months or longer Fair Value	702		746
Securities available for sale 12 months or longer Unrealized Losses	148		215
Total Securities available for sale with unrealized losses Total Fair Value	702		867
Total Securities available for sale with unrealized losses Total Unrealized Losses	148		223
Certificates of deposit
Investment [Line Items]
Securities available for sale Less than 12 months Fair Value	321		2,158
Securities available for sale Less than 12 months Unrealized Losses	2		3
Securities available for sale 12 months or longer Fair Value	399
Securities available for sale 12 months or longer Unrealized Losses	1
Total Securities available for sale with unrealized losses Total Fair Value	720		2,158
Total Securities available for sale with unrealized losses Total Unrealized Losses	3		3
Corporate debt securities
Investment [Line Items]
Securities available for sale Less than 12 months Fair Value	894		1,888
Securities available for sale Less than 12 months Unrealized Losses	3		26
Total Securities available for sale with unrealized losses Total Fair Value	894		1,888
Total Securities available for sale with unrealized losses Total Unrealized Losses	3		26
Asset-backed and other securities
Investment [Line Items]
Securities available for sale Less than 12 months Fair Value	1,555		1,376
Securities available for sale Less than 12 months Unrealized Losses	2		6
Securities available for sale 12 months or longer Fair Value			152
Securities available for sale 12 months or longer Unrealized Losses			1
Total Securities available for sale with unrealized losses Total Fair Value	1,555		1,528
Total Securities available for sale with unrealized losses Total Unrealized Losses	2		7
Other securities
Investment [Line Items]
Securities held to maturity Less than 12 months Fair Value	99
Securities held to maturity Less than 12 months Unrealized Losses	1
Securities held to maturity 12 months or longer Fair Value
Securities held to maturity 12 months or longer Unrealized Losses
Total Securities held to maturity with unrealized losses Total Fair Value	99
Total Securities held to maturity with unrealized losses Total Unrealized Losses	$ 1

[1] The number of investment positions with unrealized losses totaled 170 for securities available for sale and 3 for securities held to maturity.

[2] The number of investment positions with unrealized losses totaled 296 for securities available for sale and 3 for securities held to maturity.