Investment Securities - Investment Securities Held to Maturity (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	$ 40,712	[1]	$ 38,920	[1]
Held-to-maturity securities, Unrealized Gains	225		205
Held-to-maturity securities, Unrealized Losses Other-than-Temporary	(1)		(1)
Held-to-maturity securities, Unrealized Losses Other	(547)		(756)
Held-to-maturity securities, Fair Value	40,389		38,368
U.S. Treasury and agencies [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	1,984		3,114
Held-to-maturity securities, Unrealized Gains	3		5
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other	(59)		(79)
Held-to-maturity securities, Fair Value	1,928		3,040
Mortgage-backed securities Residential [Member] | Agency [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	38,593		35,671
Held-to-maturity securities, Unrealized Gains	209		187
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other	(476)		(665)
Held-to-maturity securities, Fair Value	38,326		35,193
Mortgage-backed securities Residential [Member] | Non-agency Non-prime [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	1		1
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	1		1
Collateralized Debt/Loan Obligation Asset-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost
Held-to-maturity securities, Unrealized Gains	9		9
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	9		9
Asset-backed securities Other [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	15		16
Held-to-maturity securities, Unrealized Gains	4		4
Held-to-maturity securities, Unrealized Losses Other-than-Temporary	(1)		(1)
Held-to-maturity securities, Unrealized Losses Other	(1)		(1)
Held-to-maturity securities, Fair Value	17		18
Obligations of state and political subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	11		12
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	11		12
Obligations of foreign governments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	9		7
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	9		7
Other debt securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	99		99
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other	(11)		(11)
Held-to-maturity securities, Fair Value	$ 88		$ 88

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.